AQL Statistical Reasoning and Probability 2 — Questions and Answers
Question 1: What is the difference between 'correlation' and 'causation'?
- Correlation shows two variables move together; causation means one variable directly causes the other (Correct answer)
- Correlation and causation are interchangeable terms in statistics
- Causation means two variables are observed together; correlation means one causes the other
- Correlation requires an experiment; causation can be shown from observational data
Correct answer: Correlation shows two variables move together; causation means one variable directly causes the other
Correlation means two variables tend to change together, but causation requires evidence that one variable directly produces a change in the other.
Question 2: In statistics, an 'outlier' is best described as:
- A data point that is far removed from the rest of the data set (Correct answer)
- The average value in a data set
- The most frequently occurring value
- The midpoint of the data range
Correct answer: A data point that is far removed from the rest of the data set
An outlier is an unusually high or low value relative to the rest of the data, which can significantly affect the mean and range of a data set.
Question 3: A bag contains 5 red marbles and 3 blue marbles. What is the probability of randomly selecting a blue marble?
- 3/8 (Correct answer)
- 3/5
- 5/8
- 1/3
Correct answer: 3/8
There are 3 blue marbles and 8 total marbles (5 + 3), so the probability = 3/8.
Question 4: What does a 'sample' represent in statistical research?
- A subset of the population selected for study (Correct answer)
- The entire group being studied
- The result of a statistical test
- The margin of error in a survey
Correct answer: A subset of the population selected for study
A sample is a smaller, selected subset of a larger population, used to make inferences about the whole group.
Question 5: Which measure of central tendency is most affected by extreme values (outliers)?
- Mean (Correct answer)
- Median
- Mode
- Range
Correct answer: Mean
The mean is calculated using all data values, so a single extreme outlier can pull it significantly up or down, making it sensitive to outliers.
Question 6: If the probability of event A occurring is 0.3, what is the probability that event A does NOT occur?
- 0.7 (Correct answer)
- 0.3
- 1.3
- 0.03
Correct answer: 0.7
The complement rule states that P(not A) = 1 − P(A) = 1 − 0.3 = 0.7.
AQL Statistical Reasoning and Probability 2
What is the difference between 'correlation' and 'causation'?