UExcel Statistics 2 — Questions and Answers
Question 1: What is a Type I error in hypothesis testing?
- Failing to reject a false null hypothesis
- Rejecting a true null hypothesis (Correct answer)
- Accepting the alternative hypothesis incorrectly
- Using a sample that is too small
Correct answer: Rejecting a true null hypothesis
A Type I error (false positive) occurs when a true null hypothesis is incorrectly rejected.
Question 2: Which measure of central tendency is most affected by extreme outliers?
- Mode
- Median
- Mean (Correct answer)
- Range
Correct answer: Mean
The mean is most sensitive to outliers because it incorporates every value in its calculation.
Question 3: In a box plot, the box itself represents:
- The range of the entire dataset
- The interquartile range (IQR) (Correct answer)
- The standard deviation
- The mean plus or minus one standard deviation
Correct answer: The interquartile range (IQR)
The box in a box plot spans from Q1 to Q3, representing the interquartile range.
Question 4: What does a confidence interval of 95% mean?
- There is a 95% chance the parameter is in the interval
- If sampling were repeated many times, 95% of intervals would contain the true parameter (Correct answer)
- The sample statistic equals the population parameter 95% of the time
- 95% of data values fall within the interval
Correct answer: If sampling were repeated many times, 95% of intervals would contain the true parameter
A 95% confidence interval means that 95% of such intervals constructed from repeated samples would contain the true population parameter.
Question 5: Which type of variable can take any value within a range?
- Discrete variable
- Nominal variable
- Continuous variable (Correct answer)
- Ordinal variable
Correct answer: Continuous variable
A continuous variable can take any value within a range, including fractional values.
Question 6: What is the purpose of a chi-square test?
- To compare two population means
- To test the relationship between categorical variables (Correct answer)
- To calculate standard deviation
- To determine regression coefficients
Correct answer: To test the relationship between categorical variables
The chi-square test assesses whether there is a significant association between two categorical variables.
UExcel Statistics 2
What is a Type I error in hypothesis testing?