Question 1

Which of the following best describes the difference between descriptive and inferential statistics?

Accepted Answer

Descriptive statistics summarize and organize data, while inferential statistics use sample data to make generalizations about a population.

Question 2

A researcher collects blood pressure readings from a random sample of 100 adults. Which type of variable is blood pressure?

Accepted Answer

Continuous

Question 3

Which of the following is the correct formula for the sample mean $$\bar{x}$$?

Accepted Answer

$$\bar{x} = \frac{\sum_{i=1}^{n} x_i}{n}$$

Question 4

A hospital wants to compare the average recovery time after surgery between two different drugs. Which statistical test is most appropriate?

Accepted Answer

Independent samples t-test

Question 5

Which of the following is NOT an assumption of the independent samples t-test?

Accepted Answer

The data are paired.

Question 6

Given a normal distribution with mean $$\mu = 100$$ and standard deviation $$\sigma = 15$$, what is the z-score for a value of $$x = 130$$?

Accepted Answer

$$z = \frac{130 - 100}{15} = 2.0$$

Question 7

Which of the following best describes a Type I error?

Accepted Answer

Rejecting a true null hypothesis

Question 8

A study finds a p-value of 0.03 when testing the effect of a new drug. If the significance level $$\alpha is $$set at 0.05, what is the correct interpretation?

Accepted Answer

The result is statistically significant, and the null hypothesis should be rejected.

Question 9

Which formula correctly represents the calculation of variance for a sample?

Accepted Answer

$$s^2$$ = \frac{\sum_{i=1}^{n} (x_i - \bar{x}$$)^2$$}{n-1}$$

Question 10

Which of the following is a correct interpretation of a 95% confidence interval for a population mean?

Accepted Answer

If we were to take many samples and build a confidence interval from each, about 95% of those intervals would contain the population mean.

Question 11

Which of the following is the formula for the standard error of the mean?

Accepted Answer

$$SE = \frac{s}{\sqrt{n}}$$

Question 12

A researcher wants to test if there is an association between smoking status (smoker/non-smoker) and lung cancer (yes/no). Which statistical test should be used?

Accepted Answer

Chi-square test

Question 13

Which of the following is the correct formula for the odds ratio (OR) in a 2x2 table?

Accepted Answer

$$OR = \frac{ad}{bc}$$

Question 14

Which of the following is a property of the normal distribution?

Accepted Answer

It is symmetric about the mean.

Question 15

If the sensitivity of a diagnostic test is 90% and the specificity is 80%, what does the sensitivity represent?

Accepted Answer

The probability that a diseased person tests positive.

Question 16

Which of the following is the formula for the positive predictive value (PPV)?

Accepted Answer

$$PPV = \frac{TP}{TP + FP}$$

Question 17

Which of the following is the correct formula for the relative risk (RR)?

Accepted Answer

$$RR = \frac{a/(a+b)}{c/(c+d)}$$

Question 18

A boxplot is useful for displaying which of the following?

Accepted Answer

The distribution, median, quartiles, and outliers of a quantitative variable

Question 19

Which of the following is the formula for the 95% confidence interval for a mean when the population standard deviation is unknown?

Accepted Answer

$$\bar{x} \pm t_{\alpha/2, n-1} \cdot \frac{s}{\sqrt{n}}$$

Comprehensive Study Notes for College Statistics: Biostatistics and Data Analysis

Guida di studio - Domande di pratica

Study guide - Flashcard