Executive PrepLab · V2 · Practice 1

Assumption, Strengthen, Weaken, Evaluate

Layer 1 is shared by all four types, because all four ask about the same thing: the gap between the premises and the conclusion. If you can find the conclusion and name the gap in your own words, the question type only tells you what to do with it. If you cannot, no amount of technique per type will help.

So the drills come first, and they are not optional. Sixteen short arguments, no answer choices. Find the conclusion; name the gap.

Layer 2 is eight items per type, ramped from clean to disguised.

Layer 3 diagnoses what your specific errors mean.

Layer 1

Structure drills

Shared by all four question types below — the anatomy work that every one of them depends on. No options: write your answer, then open the model answers for the set.

Drill set A · Find the conclusion

For each, write down which sentence is the conclusion. Use the because test from V1.2: put "because" between your candidate and the rest, and see whether it reads forward or backward.

A1. The reservoir has lost a third of its capacity to sediment since it was

A2. The hospital should extend its physiotherapy hours into the evening.

A3. Rail freight produces roughly a quarter of the emissions of road haulage

A4. Supporters of the sugar levy point to the fall in consumption since it

A5. Several councils have adopted four-day collection schedules and reported

A6. Because the fungus spreads only through root contact, and because the

A7. The museum’s attendance rose 18 percent in the year after it abolished

A8. It is often argued that the decline of the fishery is a consequence of

	Conclusion	Note
A1	The authority should dredge the reservoir.	Last sentence, standard shape
A2	The hospital should extend its physiotherapy hours.	First sentence; the second is the reason
A3	Shifting the container traffic to rail would cut emissions substantially.	Middle; signalled by therefore, with a concession after
A4	The levy cannot be credited with the reduction.	Opens with the opposed view — the trap from V1.2
A5	The savings come from reduced overtime rather than from fewer vehicle-hours.	The conclusion is a diagnosis, not a recommendation
A6	The outbreak in the eastern plantation must have a separate origin.	Two because clauses announce that the conclusion follows
A7	Free admission has widened the museum’s audience.	Last sentence, no signal word
A8	The decline is not a consequence of warming water.	Unstated as such — the argument rejects a view without restating its own in one sentence

A8 is worth sitting with. The conclusion is implied by however plus the evidence: the passage rejects the warming explanation without ever writing "the warming explanation is wrong." Arguments in this format do that regularly, and the answer choices will state it plainly.

Drill set B · Name the gap

For each, state in one sentence what must be true for the conclusion to follow. Then check yourself with the negation test: if the opposite were true, would the argument fail?

B1. Employees who use the standing desks report fewer back complaints than

B2. The new signalling system was installed in March. Delays on the line fell

B3. Every one of the vineyard’s twelve plots that was treated with the new

B4. Sales of the illustrated edition outpaced those of the plain edition

B5. The clinic reduced its no-show rate by sending appointment reminders by

B6. A survey of visitors leaving the exhibition found that 82 percent rated

B7. Since the bypass opened, traffic through the town centre has fallen by

B8. The library’s loans of physical books have fallen every year for a

	The gap	Negation test
B1	That the benefit comes from the desks rather than from who chooses them, and that it transfers to people who did not choose	If the standing-desk users were already healthier, the argument collapses
B2	That nothing else in that period reduced delays — no timetable change, no seasonal effect	If April–September is simply the low-delay half of the year, the argument collapses
B3	That the plots would not have produced a heavier crop anyway — no favourable weather, no other change	If it was an exceptional season everywhere, the argument collapses
B4	That the difference reflects preference rather than price, availability or promotion	If the plain edition was out of stock for half the period, the argument collapses
B5	That other clinics resemble this one in the ways that made reminders work	If their patients miss appointments for reasons reminders do not address, the argument collapses
B6	That people who left early or did not attend do not differ systematically from those surveyed	If the dissatisfied left before the exit survey, the argument collapses
B7	That the traffic did not simply move elsewhere in the region	If the bypass is now congested, the argument collapses
B8	That physical loans are a reliable proxy for reading	If borrowers shifted to e-books or bought more, the argument collapses

The pattern in six of the eight: the premises report an association and the conclusion asserts a cause. That is V2.8, and it is the terrain most of this block is played on.

Two are different. B6 is a sampling gap — who was measured. B8 is a proxy gap — whether the thing counted stands for the thing claimed. Learn to spot those two alongside causation, because they are the next most common.

Layer 2

Assumption

Assumption 1

The reservoir has lost a third of its storage capacity to accumulated sediment. Engineers have concluded that dredging would restore the reservoir to close to its original capacity.

Which of the following is an assumption on which the engineers’ conclusion depends?

Negate it: the sediment cannot be removed without compromising the dam. Then dredging is not available as a remedy and the conclusion fails. That is load-bearing.

A is a cost comparison the argument never makes — dredging can restore capacity whether or not it is the cheapest option. C concerns adequacy, not restoration. D is about the future, and the conclusion is about what dredging would achieve, not how long it would last. E is corroboration, which helps and is not required.

Assumption 2

A vineyard treated all twelve of its plots with a new mulch this season and harvested a heavier crop from every plot than in the previous year. The owner has concluded that the mulch increases yield.

The owner’s conclusion depends on which of the following assumptions?

Every plot was treated, so there is no control. If the season was better for reasons unrelated to mulch, the whole yield rise is explained without it. Negate B and the argument collapses.

A compares against a different treatment the argument does not mention. C and D are about the future and about price. E would matter for a different conclusion — the argument claims mulch increases yield, not that it does so uniformly.

Assumption 3

A clinic reduced its appointment no-show rate from 14 percent to 6 percent after it began sending text reminders. The regional health authority plans to introduce text reminders at its eleven other clinics in order to achieve similar reductions.

The authority’s plan assumes which of the following?

The plan requires that the mechanism transfers. If patients elsewhere miss appointments because of transport, cost or work schedules, reminders will not help them, however well they worked here. Negate C and the plan fails.

D is the near-miss and worth the extra look: technical capacity feels necessary, but the authority is planning to introduce the reminders, which presupposes it. An assumption is something the argument needs and does not say; capacity is implied by the plan itself. A, B and E are irrelevant to whether reductions follow.

Assumption 4

Since the bypass opened, traffic through the town centre has fallen by half. The county has concluded that the bypass has reduced congestion across the region.

Which of the following is an assumption required by the county’s conclusion?

The premise is about one place; the conclusion is about the region. That gap is the item. If the traffic simply moved and is now congesting somewhere else, town-centre figures fell and regional congestion did not.

C is about persistence, not about whether it happened. E would strengthen the case without being required. A and B are irrelevant.

Assumption 5

A publisher found that its illustrated edition outsold its plain edition three to one over the same six-month period. It has decided to illustrate its entire backlist, expecting comparable gains.

The publisher’s decision depends on which of the following assumptions?

Two editions sold differently — that is a correlation between edition type and sales. The conclusion attributes it to preference. If the plain edition was priced higher, promoted less, or out of stock, the difference has nothing to do with illustration.

A is a business consideration, not a requirement of the inference. D would matter for a claim about total sales, not about preference. C and E are practical matters.

Assumption 6

Because the fungus spreads only through root contact, and because the affected stands in the eastern plantation are separated from the western outbreak by more than forty metres of open ground, foresters have concluded that the eastern outbreak began independently.

The foresters’ conclusion depends on the assumption that

The argument’s own premise is that the fungus spreads only through root contact. Forty metres of open ground blocks that route only if no roots cross it. Negate B — roots do extend across — and the two outbreaks could be connected after all.

E is tempting because it also concerns transmission, but the argument does not need it: even a fungus that survives without a host still requires root contact to spread, by the stated premise. A, C and D are irrelevant to the transmission route.

Assumption 7

The museum abolished admission charges in January and recorded an 18 percent rise in attendance over the following year. The trustees have concluded that free admission has widened the museum’s audience.

Which of the following is an assumption on which the trustees’ conclusion depends?

The conclusion is about a wider audience, not more visits. If the 18 percent consists of the same people coming more often now that it is free, the audience has not widened at all. Negate C and the specific conclusion fails.

B goes the wrong way — the argument does not need previous payers to have stayed. A, D and E are about costs, competitors and the future.

Assumption 8

A study of two hundred households found that those with home insulation grants installed had reduced their heating consumption by an average of 19 percent. The energy ministry has concluded that extending the grant scheme nationally would produce comparable savings.

The ministry’s conclusion rests on which of the following assumptions?

Households that applied for grants selected themselves, and people who apply for insulation grants may be more motivated to save energy in other ways too. If they differ from the wider population, the national result will not match.

D concerns duration. A and C are comparisons the conclusion does not make. E is background.

Note the shape shared by items 2, 5, 7 and 8: a group that selected itself, or a period with no control. That is four of eight, and it is the most common assumption gap in the format.

Layer 2

Strengthen

Strengthen 1

Sediment cores from the lake bed show a sharp increase in charcoal particles at a depth corresponding to roughly 1,200 years ago. Archaeologists propose that the increase records the arrival of farming communities who cleared land by burning.

Which of the following, if true, most strengthens the archaeologists’ proposal?

The gap: charcoal could come from natural fire. Cereal pollen appearing in the same layer and not earlier ties the burning to agriculture specifically — it closes the leading alternative and supplies the missing link.

E weakens by supplying a natural cause. A and C address whether the record is reliable, which the argument already assumes. D is corroboration of the phenomenon, not of the explanation — the same alternative applies elsewhere too.

Strengthen 2

A city replaced the sodium lamps in its underpasses with white LED fixtures. Reported assaults in those underpasses fell by a third over the following year. Officials attribute the fall to improved visibility.

Which of the following, if true, most strengthens the officials’ explanation?

A control in the strengthening direction: where the lighting did not change, the assaults did not change. That rules out a citywide trend, which is the leading alternative.

E supplies an alternative cause and weakens. C makes the fall more impressive but does not tie it to visibility. D is subjective and about feeling, not incidence. A is cost.

Strengthen 3

Ornithologists have found that the local population of a wading bird has recovered since a nearby wetland was restored. They conclude that the restoration caused the recovery.

Which of the following, if true, provides the most support for their conclusion?

A reverse control. Comparable sites without restoration declined over the same period, so a regional trend cannot explain the recovery — it happened only where the cause was present.

B actually weakens: birds arriving from two hundred kilometres away suggests a wider population movement rather than a local response. C establishes a timeline consistent with the claim but does not exclude anything. A and E are background.

Strengthen 4

A school district introduced a free breakfast programme, and attendance rates rose by four percentage points the following year. The superintendent credits the programme.

Which of the following, if true, most strengthens the superintendent’s claim?

The mechanism made specific: the rise is concentrated in exactly the students the programme reached. That is much harder to explain by any general cause.

E and D are both genuine strengtheners — a control and a stable baseline — which is what makes this item worth pausing on. B is stronger than both because it links the effect to the individuals treated, rather than only excluding alternatives at the aggregate level.

Strengthen 5

A vintner argues that the unusual mineral character of the estate’s wines derives from the fractured limestone beneath the vineyard, which allows vine roots to reach an unusual depth.

Which of the following, if true, most strengthens the vintner’s argument?

The claim is that the limestone produces the character. If other estates on the same formation share it, the geology travels with the effect.

D goes the wrong way: if limestone is common everywhere, it explains nothing distinctive. B and C supply alternative causes — process and vine age. E is reputation.

Strengthen 6

Public health researchers observed that neighbourhoods with more street trees had lower rates of heat-related hospital admissions during the summer. They propose that tree canopy reduces heat exposure and therefore admissions.

Which of the following, if true, most strengthens the proposal?

The proposed mechanism is heat exposure. B measures it directly and finds a difference large enough to matter physiologically. A strengthener that demonstrates the mechanism is nearly always stronger than one that merely rules out an alternative.

A names other benefits, irrelevant to heat. C is satisfaction. D is future policy. E is background that neither helps nor hurts.

Strengthen 7

A conservation charity reintroduced beavers to a river catchment. Peak flood levels downstream in the following three winters were lower than the long-run average. The charity attributes the reduction to beaver dams slowing the release of rainfall.

Which of the following, if true, most strengthens the charity’s explanation?

The obvious alternative is that it simply rained less. B removes it: rainfall was normal, so the lower peaks were not an input effect.

D restates the effect in different units rather than supporting the cause. A, C and E are about the beavers’ history and management, not about flood mechanics.

Strengthen 8

Palaeontologists have argued that a set of parallel grooves on a fossil bone were made by a predator’s teeth rather than by later abrasion during burial.

Which of the following, if true, most strongly supports their argument?

Matching spacing to a known predator’s dentition is a fingerprint. It is hard to produce by abrasion and easy to produce by biting.

E openly weakens by confirming the alternative. B suggests a common cause acting on many bones, which favours abrasion. A implies a low-energy environment, which makes abrasion less likely and so helps slightly — but it removes an alternative where C supplies positive evidence, and positive evidence of the mechanism is stronger. D is irrelevant.

Layer 2

Weaken

Weaken 1

Employees who use the standing desks installed last year report 30 percent fewer back complaints than employees who use seated desks. The facilities director has concluded that replacing all seated desks with standing ones would reduce back complaints across the company.

Which of the following, if true, most seriously weakens the director’s conclusion?

A selection effect, and the strongest kind: the group that would most benefit deliberately excluded itself. If people with existing back problems declined the standing desks, the comparison is between healthy and less healthy people, not between desk types.

D is a control that would weaken mildly. E and A are objections to the policy on other grounds — cost and side effects — not to the reasoning. C is a single-case observation.

Weaken 2

A sugar levy was introduced two years ago, and consumption of sweetened drinks has fallen 11 percent since. The health department credits the levy.

Which of the following, if true, most undermines the department’s claim?

The effect predates the cause. A trend already running at the same rate for six years explains the 11 percent without the levy contributing anything.

B is interesting and does not weaken: reformulation is a mechanism by which the levy works. C and E are irrelevant to whether it worked. D is a small substitution effect.

Weaken 3

A university found that students who attended the optional writing workshop received higher marks on their final essays than students who did not attend. The university plans to make the workshop compulsory.

Which of the following, if true, casts the most doubt on the university’s plan?

Self-selection plus a filter: giving up a Saturday morning selects for students already invested. Making the workshop compulsory removes exactly the selection that produced the result.

B is one-case. D suggests the content is available elsewhere, which weakens slightly but does not touch the causal inference. A and E are about delivery and weighting.

Weaken 4

Since a fishery introduced a minimum landing size for the species, the average size of fish caught has increased. Managers conclude that the stock is recovering.

Which of the following, if true, most seriously weakens the managers’ conclusion?

A measurement artefact. If undersized fish are caught and discarded dead, the average size landed rises while the stock does not recover at all — possibly the reverse, since the discarded fish are lost.

B is a genuine alternative cause and the second-best answer. A weakens the regulation’s design without touching the size observation. D and E are context.

Weaken 5

A retailer introduced a loyalty card and found that cardholders spend 40 percent more per year than non-cardholders. The retailer concludes that the card increases customer spending.

Which of the following, if true, most weakens the retailer’s conclusion?

Reverse causation, near enough: the heaviest spenders signed up, rather than signing up causing heavy spending. The correlation survives with no effect from the card.

A supplies a small mechanism that would strengthen. C, D and E are administrative.

Weaken 6

A city introduced a congestion charge for the central zone. Journey times within the zone have fallen by 14 percent. The transport authority concludes that the charge has improved traffic flow in the city.

Which of the following, if true, most seriously undermines the authority’s conclusion?

Displacement. The measured improvement is inside the zone; the conclusion is about the city. A 21 percent rise on the ring road suggests total congestion did not fall, it moved.

A is displacement in time and weakens mildly. D would strengthen. C and E are objections to the policy, not to the inference.

Weaken 7

Researchers found that people who eat oily fish at least twice a week have a lower incidence of a particular inflammatory condition. They conclude that compounds in oily fish protect against the condition.

Which of the following, if true, most weakens the researchers’ conclusion?

A common cause — or rather, a bundle of them. If fish eaters also exercise more and smoke less, the difference in incidence may owe nothing to fish.

A strengthens. D is about where the compounds occur, not whether they act. E is a single-case objection. C is cost.

Weaken 8

A publisher observed that its titles with cover art by a particular designer sold better than its other titles. It has commissioned the designer for its entire forthcoming list.

Which of the following, if true, most seriously weakens the reasoning behind the publisher’s decision?

Reverse causation, cleanly. The designer was given the titles already expected to sell well, so the covers followed the sales potential rather than producing it. Commissioning the designer for everything gets none of what produced the correlation.

C is intriguing but ambiguous — a cover can work without being identifiable. A and D are commercial matters. E is true of everything and weakens nothing in particular.

Layer 2

Evaluate

Evaluate 1

A hospital plans to reduce readmission rates by telephoning every discharged patient within 48 hours to check on their recovery. Since most readmissions follow complications that develop in the first week, the hospital expects the calls to catch problems early.

Which of the following would be most useful to determine in evaluating the hospital’s plan?

Two-answer test. If complications are detectable by telephone, the plan works as described. If they are not — if they present as a fever or a wound appearance the patient cannot report — the calls catch nothing. Opposite directions.

A, C, D and E all leave the plan’s prospects unchanged either way. D is the closest miss: who makes the call matters only if it bears on detection, and the option does not say it does.

Evaluate 2

A city plans to reduce winter air pollution by offering grants for replacing wood-burning stoves with electric heating. Wood smoke accounts for roughly 40 percent of the city’s winter particulate emissions.

Which of the following would be most useful to determine in evaluating the plan?

If the electricity is generated from particulate-emitting sources near the city, the plan moves the emissions rather than removing them. If it is not, the 40 percent is genuinely displaced.

B concerns uptake, which matters for scale but not for whether the mechanism works — and note the plan does not claim full replacement. C, D and E are context.

Evaluate 3

A farm plans to reduce its water use by switching from overhead sprinklers to drip irrigation, which delivers water directly to the root zone and loses far less to evaporation.

Which of the following would be most useful to determine in evaluating the plan?

The mechanism requires that drip lines reach the roots. If the crops root deeper than the lines deliver, the water is lost anyway or the crops suffer. Yes and no point in opposite directions.

A is maintenance cost, not water use. B, D and E are irrelevant to whether the switch reduces consumption.

Evaluate 4

A publisher plans to increase revenue by releasing its backlist as audiobooks, on the grounds that audiobook sales in the category have grown 20 percent annually for five years.

Which of the following would be most useful to determine in evaluating the publisher’s plan?

The goal is increased revenue. If audiobook growth is cannibalising print sales of the same titles, the publisher gains a format and loses a market. If it is new listeners, the revenue is additional.

This is the item where the goal, not the mechanism, is where the evaluation bites. B affects margin rather than revenue. C, D and E are peripheral.

Evaluate 5

A rail operator plans to improve punctuality by lengthening the scheduled journey time on its busiest route by six minutes, absorbing the delays that currently accumulate along the line.

Which of the following would be most useful to determine in evaluating the plan?

If six minutes covers the delays that typically occur, punctuality improves. If typical delays run to fifteen minutes, the padding absorbs little and the plan achieves nothing.

A is about passenger preference, a different goal. C, D and E do not bear on whether the padding works.

Evaluate 6

A council plans to reduce fly-tipping by opening the municipal waste site on Sundays, reasoning that much illegal dumping occurs at weekends when the site is closed.

Which of the following would be most useful to determine in evaluating the plan?

The plan assumes opening hours are the constraint. If people fly-tip to avoid disposal charges rather than because the site is shut, Sunday opening changes nothing.

D is a cost consideration. A, C and E are context that leaves the mechanism untouched.

Evaluate 7

A brewery plans to reduce its energy costs by recovering heat from the boiling stage and using it to pre-warm incoming water. The boiling stage accounts for the largest single share of the brewery’s energy consumption.

Which of the following would be most useful to determine in evaluating the plan?

Heat recovery works only if the heat can be used. Brewing is a batch process; if the recovered heat dissipates before the next cycle, there is nothing to pre-warm with.

B affects the value of the saving, not whether there is one. D is a different plan. C and E are peripheral.

Evaluate 8

A conservation body plans to protect a declining butterfly by restoring the grassland on which its caterpillars feed. Surveys have found the butterfly only where that grassland type survives.

Which of the following would be most useful to determine in evaluating the plan?

Restoring habitat helps only if the butterfly can reach it. If the restored grassland lies beyond dispersal range from surviving colonies, it will sit empty.

E is background — that it was once widespread does not tell you it can recolonise now. B, C and D are about the species elsewhere, other benefits, and cost.

Answer as many as you like, then check — it scores what you have answered so far, across all 32 items.

Layer 3

Diagnosis

Check your answers above, then read this. The pattern of what you missed matters more than how many.

If you missed	It means	Go back to
Assumption 2, 5, 7, 8	You accept a helpful fact as a necessary one	V2.1, and use the negation test on every option
Assumption 3 (chose D)	You treat what the plan presupposes as an assumption of the argument	V2.1
Strengthen 1, 5	You accept corroboration of the phenomenon as support for the explanation	V2.2
Strengthen 4, 6	You do not distinguish ruling out an alternative from showing the mechanism	V2.2
Weaken 1, 3, 5, 8	Selection effects and reverse causation not automatic	V2.8, drills B1–B5
Weaken 4, 6	Measurement artefacts and displacement not recognised	V2.3
Any Weaken where you chose a cost or preference option	You are attacking the topic, not the reasoning	V2.3
Evaluate, any	You are not running yes and no separately	V2.4

The cross-cutting diagnosis. Count how many of your errors across all 32 items were on causal arguments — premises reporting an association, conclusion asserting a cause. If it is more than half, the fix is not more items. It is V2.8 and drill set B, because you are not recognising the shape early enough to know what the answer will look like.