Data Collection & Analysis Flashcards

A trial reports p = 0.03 for the difference between treatment groups. Which interpretation is correct?

Answer: If there were truly no difference, results at least this extreme would occur about 3% of the time

A p-value is the probability of getting results this extreme or more if the null hypothesis were true.

Concluding that a drug works when it actually has no effect is which type of error?

Answer: Type I error

A Type I error is a false positive, meaning a true null hypothesis is rejected, and its probability is set by alpha.

If a study has a beta of 0.20, what is its statistical power?

Answer: 0.80

Power equals 1 minus beta, so 1 - 0.20 = 0.80.

Length-of-stay data are strongly right-skewed by a few very long admissions. Which measure of central tendency best describes the typical patient?

Answer: Median

The median is not pulled toward extreme values, so it describes skewed data better than the mean.

Which statistic describes how spread out individual values are around the mean?

Answer: Standard deviation

Standard deviation measures how much individual observations vary around the mean.

Researchers want to test whether smoking status (yes/no) is associated with disease status (yes/no). Which test is most appropriate?

Answer: Chi-square test

The chi-square test checks for association between two categorical variables in a contingency table.

The same participants have cholesterol measured before and after a diet program. Which test compares the two means?

Answer: Paired t-test

A paired t-test is used when two measurements come from the same subjects.