About Cause and Effect
A cause and effect question gives two statements and asks which of four fixed relations holds between them: that the first causes the second, that the second causes the first, that both are effects of causes that are independent, or that both are effects of one common cause. The four answers never change, so the work is entirely in reading the two statements. One answer is recorded for each pair and the explanation gives the reason, together with the relation that is easiest to confuse with it.
What you need to understand
- The four answers are fixed and worth learning by heart: statement I causes statement II; statement II causes statement I; both are effects of independent causes; both are effects of a common cause.
- The first question to ask is which of the two came first, because a cause precedes its effect. The order in which the statements are printed tells you nothing, and the second statement is as likely to be the cause as the first.
- The second question is whether either statement could have brought the other about. Many pairs are settled by that alone, because a fall in demand cannot cause a rise in a price while a rise in a price can cause a fall in demand.
- If neither statement could have produced the other, and no single event behind both can be named, the two are effects of independent causes.
- If neither could have produced the other but one event behind both can be named, they are effects of a common cause. Rain is the standard example: it explains both umbrella sales and taxi journeys.
- The common cause is often not stated. Supplying it is part of the work, and if you cannot supply one for a pair that is otherwise unrelated, the answer is that the two are independent.
- Reversal is the commonest trap. A falling demand for a service and a cut in that service look alike, and only the order tells you which explained the other.
- Two patterns worth memorising. A change in the price of something is normally a cause, and the change in how much of it is bought is normally the effect rather than the reverse.
- The same holds for a change in the quality or convenience of a service, such as its hours or its frequency: the change in the service is the cause and the change in its use is the effect.
- Two effects of a common cause tend to rise and fall together, because one event is producing both. Two effects of independent causes have no reason to move together at all.
- A statement that already contains the word because, or that names its own reason, is usually an effect with its cause written into it. That makes it a poor candidate for being the cause of the other statement.
- The relation is not always between two changes of the same kind. A bank closing branches and a water main bursting are independent, while flights being cancelled and taxi queues forming are effects of one disruption.
- The test that catches most errors is to tell the story forwards. Take the pair in the order the answer claims and see whether the second follows from the first in time and in sense.
How to work through these questions
- Read both statements and say what each one is about before looking at the options. Naming the subject of each is often enough to see whether they belong together at all.
- Ask which statement could have produced the other. If only one direction makes sense, the answer is that direction.
- If neither could have produced the other, ask whether one event could lie behind both. If you can name it, the answer is a common cause; if you cannot, the two are independent.
- Where both directions seem possible, decide on chronology: which of the two records something that must have happened first.
- Never choose the reverse direction merely because the two statements are printed in a suggestive order.
- Watch for a statement that names its own cause, which usually means that statement is an effect and cannot be the cause of the other.
Mistakes that cost marks
- Choosing the reversed relation because the second statement reads like a consequence of the first.
- Calling two statements independent when a single event plainly explains both, which is the error to guard against in weather and price pairs.
- Calling two statements a common-cause pair when each has its own separate reason written into it.
- Being guided by the printed order, so that statement I is chosen as the cause simply because it appears first.
- Ignoring a because clause, which usually means the statement already has its cause named.
- Choosing the option that suits the subject matter in general rather than the two statements in front of you.
- Forgetting that the answer may name both statements as effects, which is correct for a large share of the pairs, so it should not be avoided as an escape route.
- Reading the two statements as a single narrative and inventing a connection between them that neither statement claims.
Worked example
Statement I: Fewer passengers bought season tickets for the ferry. Statement II: The ferry company cut two of its daily crossings. Which of these describes the relation between the two statements?
- Ask which could have caused the other. Fewer season tickets do not lead a ferry company to reduce its timetable, because a company decides its sailings on other grounds.
- A timetable with two fewer crossings is less useful to somebody who travels every day, so the change to the service is capable of explaining the fall in season ticket sales.
- The order therefore runs from statement II to statement I, which is the second of the four answers.
- The relation that looks tempting is the reverse one, and it fails on chronology: the company changed the timetable and the sales fell afterwards.
- Supplying a common cause would be further from the mark still, because there is no single event behind both statements. The answer is that statement II is the cause and statement I its effect.
Answer: Statement II is the cause and statement I is its effect
Practice questions with answers
A few Cause and Effect questions with the full solution shown, so you can see
how the method is applied before you attempt the timed set.
Question 1
Statement I: Bookings at the hotel fell in the winter.
Statement II: The hotel closed its restaurant for the winter.
Which of these states the relation between the two statements correctly?
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A
Both statements are effects of independent causes.
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B
Both statements are effects of a common cause.
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C
Statement I is the cause and statement II is its effect.
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D
Statement II is the cause and statement I is its effect.
Answer: Option D — with explanation
A hotel with no restaurant is less attractive to guests, so the closure accounts for the fall in winter bookings.
The relation to be careful of here is the neighbouring one. A fall in bookings does not close a restaurant for the winter; the closure is what guests responded to.
Two habits answer most of these: ask which statement came first, and ask whether either could have brought the other about at all. If neither could, the two are either independent or the effects of one event, and what separates those two is whether a single event behind both can be named.
Common mistakes
- "Both statements are effects of..." - the two are not independent, because statement II is what brought statement I about: Both statements are effects of independent causes.
- "Both statements are effects of..." - there is no third event behind both, because statement II is itself the cause of statement I: Both statements are effects of a common cause.
- "Statement I is the cause..." - the direction is the other way round: statement I followed statement II rather than producing it: Statement I is the cause and statement II is its effect.
Question 2
Statement I: The number of accidents on the ring road rose.
Statement II: The number of breakdowns on the ring road rose.
Which of these describes the relation between the two statements?
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A
Statement II is the cause and statement I is its effect.
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B
Both statements are effects of a common cause.
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C
Statement I is the cause and statement II is its effect.
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D
Both statements are effects of independent causes.
Answer: Option B — with explanation
Ice on the road makes cars both crash and fail. The ice is the cause of both increases.
The relation to be careful of here is the neighbouring one. Accidents do not cause breakdowns, and breakdowns do not cause accidents. Both rise together because of the condition of the road.
Two habits answer most of these: ask which statement came first, and ask whether either could have brought the other about at all. If neither could, the two are either independent or the effects of one event, and what separates those two is whether a single event behind both can be named.
Common mistakes
- "Both statements are effects of..." - the two are not independent, because one event produced both of them: Both statements are effects of independent causes.
- "Statement I is the cause..." - the two statements are not cause and effect, because one does not bring the other about: Statement I is the cause and statement II is its effect.
- "Statement II is the cause..." - the two statements are not cause and effect, because the order does not run that way either: Statement II is the cause and statement I is its effect.
Question 3
Statement I: Fewer passengers bought season tickets for the ferry.
Statement II: The ferry company cut two of its daily crossings.
Read the two statements and say which of these describes their relation.
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A
Both statements are effects of a common cause.
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B
Statement I is the cause and statement II is its effect.
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C
Statement II is the cause and statement I is its effect.
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D
Both statements are effects of independent causes.
Answer: Option C — with explanation
A timetable with fewer crossings is less useful to a regular traveller, so the cut in the service came first and the fall in season ticket sales followed it.
The relation to be careful of here is the neighbouring one. The order matters here. The company changed its timetable and the sales fell afterwards, so statement II is the cause rather than the effect.
Two habits answer most of these: ask which statement came first, and ask whether either could have brought the other about at all. If neither could, the two are either independent or the effects of one event, and what separates those two is whether a single event behind both can be named.
Common mistakes
- "Both statements are effects of..." - there is no third event behind both, because statement II is itself the cause of statement I: Both statements are effects of a common cause.
- "Both statements are effects of..." - the two are not independent, because statement II is what brought statement I about: Both statements are effects of independent causes.
- "Statement I is the cause..." - the direction is the other way round: statement I followed statement II rather than producing it: Statement I is the cause and statement II is its effect.
Question 4
Statement I: Bookings at seaside hotels rose.
Statement II: Trains to the coast were reported to be full.
What is the relation between the two statements?
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A
Statement I is the cause and statement II is its effect.
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B
Both statements are effects of a common cause.
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C
Both statements are effects of independent causes.
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D
Statement II is the cause and statement I is its effect.
Answer: Option B — with explanation
A spell of fine weather in the holiday season fills hotels and trains at the same time, so one cause explains both statements.
The relation to be careful of here is the neighbouring one. Full trains do not fill hotels by themselves and hotel bookings do not fill trains. The two rise together because of the same reason for travelling.
Two habits answer most of these: ask which statement came first, and ask whether either could have brought the other about at all. If neither could, the two are either independent or the effects of one event, and what separates those two is whether a single event behind both can be named.
Common mistakes
- "Both statements are effects of..." - the two are not independent, because one event produced both of them: Both statements are effects of independent causes.
- "Statement I is the cause..." - the two statements are not cause and effect, because one does not bring the other about: Statement I is the cause and statement II is its effect.
- "Statement II is the cause..." - the two statements are not cause and effect, because the order does not run that way either: Statement II is the cause and statement I is its effect.
Question 5
Statement I: The city introduced a congestion charge.
Statement II: Traffic entering the city centre fell by a fifth.
How are the two statements related?
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A
Statement I is the cause and statement II is its effect.
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B
Both statements are effects of independent causes.
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C
Statement II is the cause and statement I is its effect.
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D
Both statements are effects of a common cause.
Answer: Option A — with explanation
The charge made entering the centre more expensive, and the fall in traffic followed it.
The relation to be careful of here is the neighbouring one. Falling traffic does not cause a city to introduce a charge; the charge is the measure taken after the traffic was judged too heavy.
Two habits answer most of these: ask which statement came first, and ask whether either could have brought the other about at all. If neither could, the two are either independent or the effects of one event, and what separates those two is whether a single event behind both can be named.
Common mistakes
- "Both statements are effects of..." - the two are not independent, because statement I is what brought statement II about: Both statements are effects of independent causes.
- "Statement II is the cause..." - the direction is the other way round: statement II followed statement I rather than producing it: Statement II is the cause and statement I is its effect.
- "Both statements are effects of..." - there is no third event behind both, because statement I is itself the cause of statement II: Both statements are effects of a common cause.
Frequently asked questions
How do I decide when both directions seem possible?
Use chronology. A cause comes before its effect, so ask which of the two statements records something that must have happened first. Where the statements give no sequence at all, that is usually a sign that the pair is not a causal one.
What if I cannot think of a common cause?
Then the two are independent. The common-cause answer is only right when you can name the single event that produced both, as rain is the event behind umbrella sales and taxi journeys.
Is the same relation always asked about in these questions?
The four relations above are the whole of them, though papers print them in different orders, so read the options rather than relying on the letters.
Why is the reversed answer so often the trap?
Because a fall in use and a fall in service look symmetrical on the page, and only the direction of explanation tells them apart. Ask which of the two somebody decided and which of the two merely happened as a result.
Where does this topic appear in a paper?
In the reasoning sections of bank, SSC and state government papers, and in some management entrance tests. It is usually answered quickly once the two questions about order and possibility have become habits.
