Statistics Flashcards

A researcher wants to estimate the average height of students at a university. She randomly selects 50 students. This is an example of:

Answer: Simple random sampling

Randomly selecting individuals from the population without structured grouping is simple random sampling.

The standard error of the mean is equal to:

Answer: σ / √n

Standard error = σ / √n; it measures how much sample means vary around the population mean.

Which of the following best describes a negatively skewed distribution?

Answer: The tail extends to the left

A negatively skewed distribution has a longer tail on the left side, pulling the mean below the median.

In a chi-square test of independence, the null hypothesis states that:

Answer: The two variables are independent

The null hypothesis in a chi-square test of independence is that the two categorical variables are not associated.

What does a 95% confidence interval mean?

Answer: If repeated sampling were done, 95% of such intervals would contain the true parameter

The correct frequentist interpretation is that 95% of confidence intervals constructed this way will capture the true parameter.

Which nonparametric test is the counterpart of the independent-samples t-test?

Answer: Mann-Whitney U test

The Mann-Whitney U test compares two independent groups using rank order rather than means.

In regression analysis, the coefficient of determination (R²) tells you:

Answer: The proportion of variance in Y explained by X

R² ranges from 0 to 1 and represents the fraction of variance in the dependent variable accounted for by the model.