Presentation exercise: study guide

Worked examples and pitfalls

The three-way rule on one short passage: Passage: 'The Riverton depot handled 4,200 parcels in March, a 12 percent increase on February. A night shift was introduced in January; in March it processed 40 percent of the parcels the depot handled.' Now take four statements. (1) 'The depot handled 3,750 parcels in February.' February is March divided by 1.12: 4,200 / 1.12 = 3,750 exactly, so this is True - the passage determines it even though the number is not printed. (2) 'The night shift caused the March increase.' Cannot Say. The passage puts the night shift and the increase in the same depot in the same period; it never claims one produced the other, and it never denies it either. Most candidates mark this False, reasoning correctly that correlation is not causation but then choosing the wrong label: False is reserved for statements the passage contradicts. (3) 'The night shift processed more than 1,700 parcels in March.' Forty percent of 4,200 is 1,680, which is not more than 1,700, so this is False - contradicted by arithmetic on the passage's own figures. (4) 'The depot handled more parcels in March than in January.' Cannot Say: January is mentioned only as the month the shift started, and no January volume is given.

Quantifier drift and illicit conversion: Passage: 'All accredited suppliers submit quarterly audits. Some suppliers in the northern region are accredited.' Statement A: 'Some suppliers in the northern region submit quarterly audits.' True, and it is worth seeing why the chain holds: at least one northern supplier is accredited, and every accredited supplier submits, so at least one northern supplier submits. Statement B: 'Every supplier that submits quarterly audits is accredited.' This reverses the first sentence. 'All accredited suppliers submit' leaves the door wide open for unaccredited suppliers to submit as well - perhaps voluntarily, perhaps under another rule - so the answer is Cannot Say. Turning 'all A are B' into 'all B are A' is called illicit conversion and it is the single most productive trap in this format, because the reversed sentence sounds like a paraphrase. Statement C: 'No unaccredited supplier submits quarterly audits' is the same reversal wearing a negative coat, and it is Cannot Say for the same reason. Statement D: 'All northern suppliers submit quarterly audits' is also Cannot Say: 'some are accredited' says nothing about the rest.

Asserted versus reported: Passage: 'The committee's report claims that the scheme cut waiting times by a third. Two of the four regional boards have disputed that figure.' Statement A: 'The scheme cut waiting times by a third.' Cannot Say. What the passage asserts is that a report claims this; the claim's truth is never settled, and the dispute does not settle it either. Statement B: 'At least two regional boards disagree with the report's waiting-time figure.' True, and note 'at least' - the passage says two disputed it, and two of four disputing is consistent with 'at least two'. Statement C: 'All four regional boards accept the figure.' False, directly contradicted. Statement D: 'The report is wrong.' Cannot Say. This item type appears constantly in policy and diplomacy passages, where a paragraph stacks a claim, a source, and a reaction, and the reader has to keep three different truth-conditions apart. The reliable habit is to underline the reporting verb - claims, argues, estimates, alleges, projects - and remember that everything downstream of it belongs to the source, not to the passage.

Percentages are not symmetric: Passage: 'Membership fell from 8,000 to 6,000 over two years, then recovered by 25 percent in the third year.' Statement: 'Membership at the end of year three was higher than at the start.' The fall is 2,000 on a base of 8,000, which is 25 percent. The recovery is 25 percent of the new base: 6,000 x 1.25 = 7,500. That is below 8,000, so the statement is False. The trap is elegant, because a 25 percent fall followed by a 25 percent rise feels like it should cancel. It does not: to get back from 6,000 to 8,000 you need a 33.3 percent rise, since 2,000 / 6,000 = 0.333. Whenever a verbal item states a change as a percentage, write down what the percentage is a percentage of before you touch it. A related version supplies the recovery as an absolute number instead - 'recovered by 2,000 members' - which does return the total to 8,000, and candidates who answered the first version from memory get the second one wrong.

Verbal analogies: name the relation as a sentence: Item: 'ANTISEPTIC is to INFECTION as ___ is to ___.' Options: (a) vaccine : immunity, (b) insulation : heat loss, (c) medicine : illness, (d) bandage : wound. Write the stem relation as a full sentence first: 'An antiseptic is applied in order to prevent an infection from occurring.' Now test each option against that exact sentence. Option (a) runs the other way - a vaccine is given to produce immunity, not to prevent it. Option (c) is the right family but the wrong specificity: medicine typically treats an illness that has already started. Option (d) is applied after the wound exists. Option (b) fits precisely: insulation is applied in order to prevent heat loss from occurring. The general method is the same on the simpler item types. 'BOOK is to LIBRARY as PAINTING is to ___' has canvas (the material), artist (the maker), and gallery (the place a collection is kept and shown) among its options; all three are genuine relations to 'painting', and only the third matches the stem sentence. Options in analogy items are chosen to be true statements about the words, just not the stated relation.

Two premises with 'some' prove nothing: Argument: 'Some depot managers are qualified engineers. Some qualified engineers hold a rigging certificate. Therefore some depot managers hold a rigging certificate.' This is invalid, and the way to prove it is a counter-model rather than an argument. Let the depot managers be Ana and Ben; let the qualified engineers be Ben and Cara; let the certificate holders be Cara alone. Premise one holds: Ben is a manager and an engineer. Premise two holds: Cara is an engineer with the certificate. The conclusion fails: neither Ana nor Ben holds the certificate. Since a single consistent world makes both premises true and the conclusion false, the argument cannot be valid, so in a True / False / Cannot Say framing the conclusion is Cannot Say. Two premises that both begin 'some' never combine into a conclusion, because 'some' gives you an overlap without telling you where the overlap sits. Contrast a valid pair: 'All accredited labs are inspected annually. No inspected facility is exempt from the fee.' Every accredited lab is inspected, and no inspected facility is exempt, so no accredited lab is exempt - True.

How to practise this skill

• Answer from the passage even when you know the subject. Candidates with a background in the topic score worse on verbal items than they expect, because their own knowledge quietly supplies the missing premise that turns a Cannot Say into a True.
• Run the two-worlds test on every candidate 'Cannot Say': can you imagine a world where all the passage's sentences hold and the statement is true, and another where they hold and it is false? If both, it is Cannot Say. If only the false world exists, it is False.
• Underline the quantifiers and hedges in the statement (all, some, only, most, may, must, likely) and find their counterparts in the passage. Roughly half of the wrong answers in this construct come from a single word swapped between the two.
• Budget about 25 to 30 seconds per statement rather than per passage, and read the passage once for structure before touching the statements. Re-reading the whole passage for each statement is what causes candidates to run out of time on the last set.
• Keep a wrong-answer log with one label per error: quantifier, causation, reported-versus-asserted, arithmetic, outside knowledge. A clear pattern almost always emerges within about forty items, and it is usually a single label.
• Work untimed until the three-way rule is automatic, then add the clock. Attempts are stored on this device only, so a slow first pass through a passage set costs you nothing but the time you spend on it.

Glossary

Entailment

A statement is entailed by a passage when it cannot be false while every sentence of the passage is true. Entailment is the only thing that earns a 'True' in this format; being plausible, likely, or well known does not.

Cannot Say

The verdict for a statement the passage neither entails nor contradicts. It is a claim about the passage, not about the world, which is why a statement you know to be true in real life can still be Cannot Say.

Quantifier

A word fixing how much of a group a claim covers: all, most, some, few, none, only. Swapping one quantifier for another changes the logical content completely while barely changing how the sentence reads.

Illicit conversion

The invalid move from 'all A are B' to 'all B are A', or from 'if P then Q' to 'if Q then P'. It preserves the words and destroys the logic, which is why converted sentences make such effective wrong answers.

Counter-model

A concrete, consistent scenario in which the premises hold and the conclusion fails. Producing one is the fastest possible proof that an argument is invalid, and it takes two or three named individuals.

Hedge

A qualifier such as may, could, is expected to, or is associated with. A hedged sentence in a passage cannot support an unhedged statement, and an unhedged passage sentence is not weakened by a hedged statement.

Reporting verb

A verb such as claims, argues, estimates, or alleges that attributes the following content to a source. Everything downstream of it is the source's assertion, and the passage takes no position on it.

Analogy relation

The specific link between the two stem words in an analogy item - tool and user, item and container, action and purpose. Naming it as a full sentence before reading the options removes almost all of the guesswork.

Study this next

• Verbal reasoning skill hub
• Practise the verbal reasoning bank
• Critical thinking lesson
• Reading comprehension lesson
• General civil-service aptitude suite
• Verbal reasoning lesson on Novus Learn

Where this material comes from

• Worked items written for Novus Learn. Every passage, statement set and figure above is original and invented for this lesson; no published or copyrighted test item is reproduced.
• Terminology follows standard, widely published usage in introductory logic and assessment writing - entailment, quantifier, illicit conversion, counter-model.
• Novus Learn aptitude construct registry (catalog seed) for the construct scope and the suite mapping shown in the related links.
• Public educational framing only - not affiliated with any official exam board, publisher or employer.

Worked examples and pitfalls

Agreement: find the head noun, then decide: 'The set of quarterly returns filed by the three regional offices (was / were) incomplete.' The subject is 'the set', which is singular, so 'was' is correct; 'offices' is merely the nearest noun, sitting inside a prepositional phrase that cannot supply the subject. Strike out everything between the head noun and the verb and the choice becomes obvious - 'the set was incomplete'. Next: 'Neither the manager nor the two supervisors (was / were) informed.' With neither/nor the verb agrees with the nearer of the two subjects, and the nearer one here is 'the two supervisors', so 'were' is correct. Reverse the order - 'Neither the two supervisors nor the manager was informed' - and the correct verb flips to singular, which is a useful check that you are applying the rule rather than guessing. Finally, a pair that trips experienced writers: 'A number of applications are missing' is correct, because 'a number of' functions as a plural quantifier, while 'The number of applications is rising' is also correct, because there 'the number' is a single quantity. Same three words, opposite verbs.

Dangling modifiers and the wandering 'only': 'Having reviewed the tender documents, the deadline was extended by two weeks.' An opening participial phrase attaches to the subject of the main clause, and the subject here is 'the deadline', so the sentence says the deadline reviewed the documents. It reads acceptably aloud because a listener silently supplies the missing actor, which is precisely why this error survives proofreading. Two clean fixes: name the actor as the subject - 'Having reviewed the tender documents, the panel extended the deadline by two weeks' - or drop the participle entirely - 'The panel reviewed the tender documents and extended the deadline by two weeks.' Now the limiting word. 'We only sent the invoice to three suppliers' literally says that sending was the only thing we did to those three. 'We sent the invoice to only three suppliers' says we sent it to no more than three. 'We sent only the invoice to three suppliers' says we sent nothing else. Three placements, three meanings, one word - put 'only', 'just', 'even' and 'almost' immediately before what they limit, and in a marked item the four options usually differ by nothing else.

Parallelism in a list: 'The role involves drafting reports, client liaison, and to maintain the case register.' Three items in three different grammatical forms: a gerund phrase, a noun phrase, and an infinitive. The repair is to pick one form and hold it: 'The role involves drafting reports, liaising with clients, and maintaining the case register.' Parallelism is worth its own item type because it is the most visible marker of careless list writing, and because real documents fail on it constantly - a bulleted list where two bullets start with a verb and the third starts with a noun, or a set of headings mixing questions and statements. The same rule governs correlative pairs: 'not only ... but also' must join two grammatically matching elements, so 'The report not only covers spending but also staffing' is faulty, and 'The report covers not only spending but also staffing' is correct, because the correlatives now bracket two nouns rather than a verb phrase and a noun.

Comma splice, and why 'however' is not a rescue: 'The system was offline for six hours, no backup was available.' Two independent clauses joined by a comma is a comma splice, and there are four legitimate repairs. Use a full stop: 'The system was offline for six hours. No backup was available.' Use a semicolon, which signals the two facts belong together. Add a coordinating conjunction after the comma: '... six hours, and no backup was available.' Or subordinate one clause: 'Because no backup was available, the six-hour outage could not be mitigated.' The trap is the fifth option that people reach for instinctively: 'The system was offline for six hours, however no backup was available.' However is a conjunctive adverb, not a coordinating conjunction, so it cannot join two independent clauses with a comma - the sentence is still spliced. It needs a semicolon or full stop before 'however' and a comma after it. The same applies to therefore, moreover, nevertheless, and consequently, which is why they appear so often in sentence-correction distractors.

Plain language: 37 words down to 14: Before: 'It is the recommendation of this department that consideration be given to the deferral of the implementation of the new filing procedure until such time as adequate training provision has been made available to all affected staff.' That is thirty-seven words. After: 'We recommend delaying the new filing procedure until all affected staff have been trained.' Fourteen. Look at what the rewrite actually did: it turned three nominalisations back into verbs (recommendation to recommend, deferral to delaying, provision to trained), it named the actor instead of hiding behind 'this department', and it cut 'consideration be given to' and 'until such time as', which carry no content at all. Look just as carefully at what it kept: the recommendation, the thing being delayed, and the condition that ends the delay. Plain-language items are marked on meaning preservation, not on brevity alone, and the standard wrong answer is the over-cut version - 'We recommend delaying the new procedure' - which reads beautifully and silently deletes the condition that is the substance of the recommendation. Trim the packaging, never the payload.

One incident, three readers, and the fact-inference line: Facts: the gate camera timestamps a van leaving at 11:42:00; the weighbridge camera, 300 m along the yard road, timestamps the same van at 11:42:15; the yard limit is 20 km/h. The arithmetic: 300 m in 15 s is 20 m/s, and 20 x 3.6 = 72 km/h. Now write it three ways. In the incident record: 'Vehicle VT-118 passed the gate camera at 11:42:00 and the weighbridge camera at 11:42:15. The cameras are 300 m apart, giving an average speed of 72 km/h over that section. The posted yard limit is 20 km/h.' Note what is absent: 'the driver was speeding', which is a conclusion, and 'was travelling at 72 km/h', which overstates the evidence - the figure is an average over the section, not an instantaneous speed. To the yard supervisor: lead with the decision needed and the deadline. 'Two camera timestamps put VT-118 at an average 72 km/h in a 20 km/h yard yesterday morning. I have attached the record. Can you confirm by Friday whether this goes to the safety review?' To the driver's employer: lead with the specific, verifiable reference - vehicle, date, time, the two camera points - and the single action requested. Same facts every time; what changes is which fact leads, and in a written-communication assessment the most apologetic option is rarely the best one, while any option that names blame in a record that has not been reviewed is usually the worst.

How to practise this skill

• Proofread in separate passes, one error class at a time - agreement, then modifiers, then punctuation, then numbers and names. A single pass looking for 'anything wrong' reliably finds fewer errors than three narrow passes taking the same total time.
• Read your draft aloud, or subvocalise it. Comma splices, dropped words and lost parallelism are audible even when they are invisible; dangling modifiers are the exception, which is why they need a deliberate check of what each opening phrase attaches to.
• On sentence-correction items, diagnose before you choose. Name the fault in the original in three words, then look for the option that fixes exactly that and introduces nothing new. Options that fix the fault while adding a second one are standard.
• Read every option to the end. Sentence-correction distractors commonly differ from the correct answer only in the last two or three words, and candidates who stop once the opening looks right lose marks they never see.
• For free-text tasks, spend the first minute on a three-line plan: purpose, the single action you want from the reader, and the deadline. Untimed free-text answers are usually well written and structurally shapeless, and structure is what the mark scheme can see.
• Keep a personal error list of the mistakes you actually make rather than a generic grammar checklist. Most writers repeat three or four faults, and proofreading against your own four is far faster than proofreading against forty.

Glossary

Subject-verb agreement

The requirement that the verb match the grammatical number of the subject's head noun, not of the nearest noun. Long prepositional phrases between the two are the standard way this is tested.

Dangling modifier

An introductory phrase whose implied actor is not the subject of the main clause, so the sentence attributes the action to the wrong thing. Fixed by naming the actor as the subject or by rewriting the phrase as a full clause.

Parallelism

Matching grammatical form across items in a list or across correlative pairs such as not only / but also. The commonest breach mixes gerunds, nouns and infinitives in a single series.

Comma splice

Two independent clauses joined only by a comma. Repaired with a full stop, a semicolon, a coordinating conjunction, or subordination - never by inserting however, therefore or moreover after the comma.

Nominalisation

A verb converted into a noun - implement becomes implementation, decide becomes decision. Nominalised prose hides who does what and typically doubles the word count for the same content.

Register

The level of formality and the vocabulary appropriate to a particular reader and purpose. A message can be grammatically perfect and still wrong in register, which is what free-text tasks are largely marking.

Active and passive voice

Active names the actor before the verb; passive can omit the actor entirely. Passive is legitimate when the actor is unknown or genuinely irrelevant, and evasive when it is used to avoid naming a responsible party.

Observation versus inference

An observation is what a camera, meter or witness recorded; an inference is the conclusion drawn from it. Records that mix the two are hard to defend later, because the conclusion cannot be separated from its basis.

Study this next

• Written communication skill hub
• Practise the written communication bank
• Reading comprehension lesson
• Police report writing suite
• Administrative and clerical entry suite
• Written communication lesson on Novus Learn

Where this material comes from

• Worked items written for Novus Learn. Every faulty sentence, rewrite, word count and incident figure above is original and invented for this lesson; no published or copyrighted test item is reproduced.
• Grammatical terminology follows standard, widely published usage - subject-verb agreement, dangling modifier, parallelism, comma splice, nominalisation.
• Novus Learn aptitude construct registry (catalog seed) for the construct scope and the suite mapping shown in the related links.
• Public educational framing only - not affiliated with any official exam board, publisher or employer.

Worked examples and pitfalls

The negation test finds assumptions; nothing else does: Argument: 'The council should fit bin sensors across the district. In the trial depot they cut collection trips by a fifth.' Candidate assumption A: 'The trial depot's waste pattern is broadly representative of the rest of the district.' Negate it - suppose the trial depot is nothing like the rest of the district - and the argument collapses, because a result that does not transfer supports nothing about the district. So A is a required assumption. Candidate assumption B: 'Bin sensors are the cheapest available technology for this purpose.' Negate it - suppose they are the most expensive - and the argument still stands as given, since it argued from a reduction in trips, not from cost. B is not required; it would strengthen a cost-based argument that was never made. Candidate C: 'Fewer collection trips reduce total operating cost.' Negate it and the recommendation loses its point, so C is required too, even though the argument never mentions cost. That last case is the one candidates miss, because the required assumption is what bridges the evidence to the recommendation, and bridging assumptions are by definition unstated. The failure mode across this whole item type is picking statements that support the conclusion instead of statements the argument cannot survive without.

Base rates: 90 percent accurate, 15 percent right: A production line runs an automated defect test. Defects occur in 1 percent of units. The test flags 90 percent of genuinely defective units, and wrongly flags 5 percent of good units. A unit has just been flagged - how likely is it to be defective? Work in whole units rather than probabilities. Take 10,000 units: 100 are defective and 9,900 are good. Of the 100 defective, the test flags 90. Of the 9,900 good, it wrongly flags 5 percent, which is 495. Total flags: 90 + 495 = 585. Of those, 90 are genuine, so the answer is 90 / 585 = 15.4 percent. Better than the 1 percent base rate, and nowhere near the 90 percent that intuition offers. The error has a name - confusing the probability of a flag given a defect with the probability of a defect given a flag - and it has a practical consequence: the rework queue has to be sized for 585 units a batch, not 100, and 495 of the 585 units sitting in it are perfectly good. Whenever a test, screening rule or model accuracy figure appears in an item, ask how many of the negatives there are, because with a rare condition the false positives from a large clean population swamp the true positives from a small affected one.

Three alternative explanations, and the comparison that settles it: Claim: 'Employees who attended the optional resilience workshop took 30 percent fewer sick days last year, so the workshop works.' Alternative one, selection: attendance was optional, so the people who signed up may have been the healthier and more engaged to begin with, and would have taken fewer sick days regardless. Alternative two, reverse direction: employees who were frequently unwell were the least able to attend a full-day workshop, so illness determined attendance rather than the other way round. Alternative three, a common third factor: the workshop ran on Thursday afternoons at head office, so attendance largely tracks being an office-based rather than shift-based worker, and shift workers take more sick leave for reasons that have nothing to do with resilience training. What would settle it: randomly assigning the offer to half the workforce and comparing the two groups. Failing that, the cheapest useful check already exists in the payroll data - compare attendees' and non-attendees' sick days in the year before the workshop. If attendees were already 30 percent lower, selection is doing the entire job. The habit worth building is to name the comparison group before you accept any before-and-after number.

Deduction: affirming the consequent versus modus tollens: Rule: 'If an invoice is over 10,000 euro, it requires two signatures.' Argument A: 'This invoice has two signatures, therefore it is over 10,000 euro.' Invalid - this is affirming the consequent. The rule makes two signatures necessary for large invoices; it says nothing that prevents a cautious manager from double-signing a 400 euro invoice, so a two-signature invoice of any size is consistent with the rule. Argument B: 'This invoice has only one signature, therefore it is not over 10,000 euro.' Valid - this is modus tollens, denying the consequent to deny the antecedent, and it holds assuming the rule was followed. Argument C: 'This invoice is not over 10,000 euro, therefore it does not have two signatures.' Invalid again, denying the antecedent. Two further points that deduction items test directly. First, validity is about form alone: 'All banks close on Sundays; Riverton Mutual is a bank; therefore Riverton Mutual closes on Sundays' is perfectly valid even if the first premise is false, and a valid argument with a false premise can deliver a false conclusion. Second, in these items you must accept the premises as given even when you know them to be untrue, because the question is whether the conclusion follows, not whether it is true.

Interpretation: what a survey figure does and does not license: Data: all 1,200 employees of a firm were surveyed. 62 percent said they would accept a four-day week at 90 percent pay. Of those who said yes, 71 percent were under 35. Conclusion one: 'A majority of this firm's employees would accept the trade.' This follows - 62 percent of a complete census of the firm is a majority, and the conclusion is properly limited to this firm. Conclusion two: 'A majority of the firm's under-35 employees would accept the trade.' This does not follow, and the arithmetic shows why. Sixty-two percent of 1,200 is 744 accepters, and 71 percent of 744 is about 528 accepters aged under 35. That is the composition of the accepters, not the acceptance rate within the under-35 group, and without knowing how many under-35s the firm employs the rate is undetermined: if there are 900, the rate is 528 / 900 = 59 percent; if there are 600, it is 88 percent; if there were 1,100 the rate would be below half. Conclusion three: 'The firm should move to a four-day week.' This does not follow either - a stated preference about pay says nothing about output, shift cover, customer hours or cost. Notice that conclusion two is the base-rate error from the screening example, wearing survey clothing.

Strong and weak arguments on the same question: Question: should the agency publish raw inspection scores for every site? Strong argument for: 'In the neighbouring authority, publication was followed by a measurable fall in repeat violations, which is the stated aim of the inspection regime.' It is directly about this decision, it addresses the regime's own objective, and it offers evidence - and if true it would change your view. Weak argument for: 'Yes, because transparency is always good.' Sweeping, unsupported, and it would apply identically to publishing anything at all, which is the tell. Strong argument against: 'Raw scores omit the severity weighting, so a site with one critical failure can rank above a site with six minor ones, and a member of the public cannot see the difference.' Specific, mechanistic, directly about the proposal, and it would change your view. Weak argument against: 'No, because businesses will object.' It may be true and it may matter politically, but it does not bear on whether publication achieves the regime's aim, and no evidence is offered. Two tests separate strong from weak: is the argument about the exact question asked, and would accepting it change the decision? Note that you can hold a firm personal view on publication and still be required to mark the argument on the other side as the strong one - that split is what the item type is measuring.

How to practise this skill

• Negate every candidate assumption out loud. If the argument survives the negation, it was never an assumption, however supportive it sounds. This single habit converts the assumption item type from guesswork into a mechanical check.
• Write the conclusion in your own words before reading any option. Half of the wrong answers on inference and evaluation items are responses to a conclusion the argument never reached.
• Ask 'percentage of what?' on every percentage in the stimulus and reconstruct the denominator in whole units. Base-rate and composition errors both dissolve the moment you write out counts instead of rates.
• Deliberately practise marking arguments you disagree with as strong and arguments you agree with as weak. Assessments in this construct are built to catch agreement masquerading as evaluation, and the effect is largest on politically loaded stimuli.
• For any causal claim, write two alternatives - selection and a third factor - and name the comparison group that would rule them out, before you decide whether the evidence supports the claim.
• Log wrong answers by task type rather than by topic: inference, assumption, deduction, interpretation, evaluation. Candidates are rarely weak across all five, and the profile tells you where the next hour of practice belongs.

Glossary

Conclusion

The claim an argument is trying to establish. It is not always last, is often signalled by therefore, so, or should, and locating it correctly determines every subsequent judgement about the argument.

Assumption

An unstated premise the argument requires in order to work. Identified by negation: negate it and a genuine assumption brings the argument down, while a merely helpful statement leaves it standing.

Validity and soundness

An argument is valid when the conclusion cannot be false while the premises are true, which is a property of form alone. It is sound when it is valid and the premises are actually true.

Affirming the consequent

The invalid pattern 'if P then Q; Q; therefore P'. It is the most common deductive distractor because it differs from the valid modus tollens form by only the position of a negation.

Base rate

How common something is in the population before any test or evidence is applied. Ignoring it makes accurate-sounding tests appear far more informative than they are when the condition is rare.

Confounder

A third factor associated with both the supposed cause and the outcome, capable of producing the entire observed relationship on its own. Ruled out by randomisation or by an explicit comparison group.

Selection effect

A difference between groups created by how people entered them rather than by the treatment under study. Optional programmes and voluntary surveys are where it appears most often.

Falsifiability

The property of a claim that some observation could show it to be wrong. A claim compatible with every possible result carries no information, which is why 'what would change your mind?' is a diagnostic question.

Study this next

• Critical thinking skill hub
• Practise the critical thinking bank
• Verbal reasoning lesson
• Government audit suite
• Investigator and detective reasoning suite
• Critical thinking lesson on Novus Learn

Where this material comes from

• Worked items written for Novus Learn. The arguments, survey figures, defect-test numbers and evaluation options above are original and invented for this lesson; no published or copyrighted test item is reproduced.
• The five task types named in the summary - inference, assumption, deduction, interpretation, evaluation of arguments - describe a structure used publicly across several critical-thinking assessments; no affiliation with any publisher is claimed or implied.
• Terminology follows standard, widely published usage in introductory logic and research methods - validity, soundness, affirming the consequent, base rate, confounder, selection effect.
• Novus Learn aptitude construct registry (catalog seed) for the construct scope and the suite mapping shown in the related links.
• Public educational framing only - not affiliated with any official exam board, publisher or employer.

Worked examples and pitfalls

Worked scenario: an unverified safety concern: A colleague reports a possible equipment fault while a deadline is approaching. First distinguish the known fact, the report, from the unverified cause. A strong response protects people and affected work, checks the concern through the right channel, tells the relevant lead, and records what was done. Ignoring the report underreacts; shutting down unrelated work or accusing someone before checking the facts overreacts.

Method: facts, duties, risks, response: Write four short notes before ranking options: what is known, who may be affected, which duty or boundary applies, and what safe next step is available now. Prefer an action that addresses the immediate issue and creates useful follow-through. Do not reward an option merely because it sounds decisive.

How to practise this skill

• Answer the question asked: best first action, worst action, or complete response are different tasks.
• Check whether an option acts within the person's authority and escalates only as far as the risk requires.
• When two options look reasonable, prefer the one that gathers missing facts and communicates ownership.

Glossary

Proportionality

Matching the urgency and scope of a response to the evidence, likely impact, and authority available.

Role boundary

The limit of what a person may decide or do without approval, specialist help, or escalation.

Follow-through

Confirming ownership, recording the decision, and checking that the issue was actually resolved.

Study this next

• Situational judgement test
• Workplace ethics
• Decision-making
• Situational judgment lesson on Novus Learn

Where this material comes from

• Novus Learn original situational-judgment suite scenarios and published construct mapping.
• Novus educational framework: facts, duties, risks, role boundaries, proportional action, and follow-through.

Worked examples and pitfalls

Worked scenario: two service proposals: Proposal A is cheaper and can start now; Proposal B costs more but has stronger reliability evidence. The case does not provide peak-demand data. State the decision criteria first (cost, launch timing, reliability, and demand risk), then compare only supported facts. A defensible recommendation might select a limited A pilot with a reliability threshold and request peak-demand evidence before wider rollout, rather than claiming either proposal is universally best.

Evidence matrix: Use columns for claim, supporting document, strength, contradiction, and gap. When sources conflict, report the conflict and explain how it affects confidence. Repeating every document is summary; connecting evidence to the decision criteria is analysis.

How to practise this skill

• Begin with the decision and criteria so interesting but irrelevant details do not take over.
• Use calibrated language: supported, suggests, uncertain, and conditional communicate different evidence strength.
• End with an owner, next step, and condition for revisiting the recommendation.

Glossary

Finding

A conclusion directly supported by the evidence supplied in the case.

Inference

A reasoned interpretation that goes beyond a directly stated fact and therefore needs justification.

Decision criterion

A standard used to compare options, such as cost, safety, feasibility, equity, or timing.

Study this next

• Case study
• Evidence
• Recommendation
• Case analysis lesson on Novus Learn

Where this material comes from

• Novus Learn original case-study, policy-analysis, investigation, and evidence suite scenarios.
• Novus educational framework: frame the decision, map evidence, compare alternatives, qualify confidence, and recommend.