DA Statistical Analysis 2 — Questions and Answers
Question 1: What is the interquartile range (IQR)?
- The range of the entire dataset
- The difference between Q3 and Q1 (Correct answer)
- The median minus the mean
- The variance divided by the mean
Correct answer: The difference between Q3 and Q1
The IQR is calculated as Q3 minus Q1 and represents the spread of the middle 50% of the data.
Question 2: What type of analysis examines the relationship between a dependent variable and one or more independent variables?
- Cluster analysis
- Regression analysis (Correct answer)
- Factor analysis
- Time series analysis
Correct answer: Regression analysis
Regression analysis models the relationship between a dependent variable and one or more predictors to explain or predict outcomes.
Question 3: In a box plot, what does the line inside the box represent?
- Mean
- Mode
- Median (Correct answer)
- Standard deviation
Correct answer: Median
The line inside the box of a box plot marks the median (Q2), the middle value of the dataset.
Question 4: What is Type I error in hypothesis testing?
- Failing to reject a false null hypothesis
- Rejecting a true null hypothesis (Correct answer)
- Accepting an incorrect alternative hypothesis
- Using too small a sample size
Correct answer: Rejecting a true null hypothesis
A Type I error (false positive) occurs when a true null hypothesis is incorrectly rejected.
Question 5: Which test is appropriate for comparing proportions between two independent groups?
- Paired t-test
- ANOVA
- Chi-square test (Correct answer)
- F-test
Correct answer: Chi-square test
The chi-square test of independence is used to determine if there is a significant association between two categorical variables or proportions.
Question 6: What does R-squared measure in a regression model?
- The slope of the regression line
- The proportion of variance in the dependent variable explained by the model (Correct answer)
- The statistical significance of predictors
- The residual error of predictions
Correct answer: The proportion of variance in the dependent variable explained by the model
R-squared (coefficient of determination) indicates how much of the variability in the dependent variable is explained by the independent variables.
DA Statistical Analysis 2
What is the interquartile range (IQR)?