Q: Given two mutually exclusive events $$E_1$$ and $$E_2$$ with $$P(E_1$) = 0.3$$ and $$P(E_2$) = 0.5$$, what is $$P(E_1$ \\text{ or } E_2$)$$?

$$P(E_1$ \\text{ or } E_2$) = 0.8$$

Q: Which of the following increases the likelihood of committing a Type II error?

Setting a very low alpha level (e.g., $$\\alpha = 0.01)$$

Q: Which of the following is the correct formula for conditional probability?

$$P(A|B) = \\frac{P(A \\text{ and } B)}{P(B)}$$

Q: Which of the following is true about the alpha level ($$\\alpha) in $$hypothesis testing?

Decreasing $$\\alpha$$ increases the likelihood of a Type II error.

Question 1

A researcher wants to determine if the mean systolic blood pressure of a sample of 13-year-old children differs from the national average of 113 mmHg. Which statistical test should be used and why?

Accepted Answer

One-sample t-test, because the sample mean is compared to a known value.

Question 2

Which correlation coefficient is most appropriate for assessing the relationship between two continuous variables such as height and weight?

Accepted Answer

Pearson correlation

Question 3

If the probability of a student being female in a class is $$P(	ext{female}) = 0.92$$, what is the probability that a student is male?

Accepted Answer

$$P(	ext{male}) = 0.08$$

Question 4

Which of the following best describes a Type I error in hypothesis testing?

Accepted Answer

Rejecting the null hypothesis when it is actually true.

Question 5

A study finds $$p = 0.03$$ for a t-test with $$\alpha = 0.05. $$What does this mean?

Accepted Answer

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

Question 6

Which test would you use to compare the mean age among three political groups (Democrat, Republican, Independent)?

Accepted Answer

One-way ANOVA

Question 7

Given two mutually exclusive events $$E_1$$ and $$E_2$$ with $$P(E_1$) = 0.3$$ and $$P(E_2$) = 0.5$$, what is $$P(E_1$ \text{ or } E_2$)$$?

Accepted Answer

$$P(E_1$ \text{ or } E_2$) = 0.8$$

Question 8

A test for coronary artery disease (CAD) has a sensitivity of 0.80. What does this mean in terms of conditional probability?

Accepted Answer

The probability of a positive test given the patient has CAD is 0.80.

Question 9

Which correlation should be used to assess the association between an ordinal variable and a continuous variable?

Accepted Answer

Spearman correlation

Question 10

If $$P(A) = 0.4$$, $$P(B) = 0.5$$, and $$P(A \text{ and } B) = 0.2$$, what is $$P(A \text{ or } B)$$?

Accepted Answer

$$P(A \text{ or } B) = 0.7$$

Question 11

A researcher wants to know if there is a relationship between two dichotomous variables (e.g., gender and marijuana use). Which correlation coefficient should be used?

Accepted Answer

Phi coefficient

Question 12

Which of the following increases the likelihood of committing a Type II error?

Accepted Answer

Setting a very low alpha level (e.g., $$\alpha = 0.01)$$

Question 13

A study compares systolic blood pressure between smokers and non-smokers. Which test is most appropriate?

Accepted Answer

Independent samples t-test

Question 14

Which of the following best describes the meaning of a p-value?

Accepted Answer

The probability of observing the data, or something more extreme, if the null hypothesis is true.

Question 15

If you want to test whether the mean height differs across five age cohorts, which statistical test should you use?

Accepted Answer

One-way ANOVA

Question 16

Which of the following is the correct formula for conditional probability?

Accepted Answer

$$P(A|B) = \frac{P(A \text{ and } B)}{P(B)}$$

Question 17

A regression analysis yields the equation $$Y = 69 + 1X. If a $$student scores 80 on homework 2, what is the predicted midterm grade?

Accepted Answer

$$Y = 149$$

Question 18

Which test would you use to determine if the mean of a variable changes across three time points in the same group of subjects?

Accepted Answer

Repeated measures ANOVA

Question 19

If the probability of getting heads on a single coin toss is 0.5, what is the probability of getting heads three times in a row?

Accepted Answer

$$0.125$$

Question 20

Which of the following is true about the alpha level ($$\alpha) in $$hypothesis testing?

Accepted Answer

Decreasing $$\alpha$$ increases the likelihood of a Type II error.

Statistical Methods and Probability: Final Review Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard