Test on Scientific Reasoning: Correlation and Causation

Question 1: Can a correlation be concluded as due to cause if all variables that could be affecting the result have been controlled?

A. Yes

B. No

Explanation: The study materials state that you can only conclude that a correlation is due to cause when all the variables that could be affecting the result have been controlled.

Question 2: When writing a conclusion, it is necessary to use specific data from the results to justify the conclusion.

A. Yes

B. No

Explanation: To justify a conclusion, it is necessary to back it up with specific data from the results, for example, stating that 'The rate of this reaction was 6 cm²/s faster using catalyst B compared with catalyst A'.

Question 3: A study found that a specific plant fertilizer, 'GrowFast,' increased the height of tomato plants by an average of 15% in a controlled greenhouse experiment over a 10-week period. Based ONLY on this data, which of the following conclusions is valid?

A. GrowFast fertilizer consistently increases the height of all types of plants in any environment.

B. GrowFast fertilizer increased the height of tomato plants by 15% over 10 weeks in the greenhouse experiment.

C. GrowFast fertilizer is the most effective fertilizer available for increasing plant height.

D. GrowFast fertilizer will increase the height of tomato plants in a garden by exactly 15%.

Explanation: The study materials emphasize that conclusions must strictly match the data and not go any further. Option 1 concludes 'all types of plants in any environment,' which extends far beyond the data on tomato plants in a greenhouse. Option 2 directly states what the data shows: 'GrowFast fertilizer increased the height of tomato plants by 15% over 10 weeks in the greenhouse experiment.' Option 3 claims 'most effective fertilizer available,' which is not supported by the data provided. Option 4 assumes the exact same result 'in a garden,' which is a different environment than the 'controlled greenhouse experiment' and goes beyond what the specific data shows.

Question 4: According to the provided study materials, which of the following are potential reasons why a correlation between two variables might NOT mean one variable is causing a change in the other?

A. The observed correlation could be purely coincidental or due to chance.

B. There might be a third, unmeasured variable that is influencing both variables, creating the appearance of a direct link.

C. One variable is causing the other, but the experiment was not designed to detect it.

D. The correlation is always a direct causal link if the data shows a strong relationship.

Explanation: The study materials explicitly state three possible reasons for a correlation: CHANCE (the correlation is a fluke), LINKED BY A 3RD VARIABLE (a third variable is affecting both), or CAUSE (one variable truly causes the other, but only concluded after controlling all other variables). Options 0 and 1 directly reflect the 'CHANCE' and 'LINKED BY A 3RD VARIABLE' reasons where correlation does not imply causation. Option 2 describes a scenario where causation might exist but wasn't detected, which is not one of the reasons given for correlation *not* implying cause. Option 3 is incorrect because the materials emphasize that correlation does not necessarily mean cause, even with a relationship.

Question 5: A student's personal opinion that a study page is dull allows them to conclude that the page is objectively dull.

A. Yes

B. No

Explanation: Finding a page dull personally does not mean one can conclude it is objectively dull, as others may find it interesting.