Quizizz Exam

A score (X) is 85, the mean (μ) is 75, and the standard deviation (σ) is 5. Calculate the z-score.

• -2

• 0

• 1

• 2

Answer explanation

To calculate the z-score, use the formula: z = (X - μ) / σ. Here, z = (85 - 75) / 5 = 10 / 5 = 2. Thus, the correct answer is 2.

The standard deviation (SD) is 12 and the sample size (n) is 36. Calculate the Standard Error of the Mean (SEM).

• 6

• 2

• 12

• 2

Answer explanation

The Standard Error of the Mean (SEM) is calculated using the formula SEM = SD / √n. Here, SD = 12 and n = 36, so SEM = 12 / √36 = 12 / 6 = 2. Thus, the correct answer is 2.

In a one-sample t-test, the sample mean (M) is 52, the population mean (μ) is 50, and the standard error of the mean (SEM) is 1. Calculate the t-statistic.

• 0.5

• 1

• 1.5

• 2

Answer explanation

To calculate the t-statistic, use the formula: t = (M - μ) / SEM. Here, t = (52 - 50) / 1 = 2. Thus, the correct answer is 2.

For a one-sample t-test with a sample size (n) of 21, what are the degrees of freedom (df)?

• 22

• 20

• 1

• 20

Answer explanation

In a one-sample t-test, the degrees of freedom (df) are calculated as n - 1. With a sample size (n) of 21, the degrees of freedom are 21 - 1 = 20. Therefore, the correct answer is 20.

In a one-sample t-test, the sample mean (M) is 60, the population mean (μ) is 55, and the sample standard deviation (s) is 10. Calculate Cohen's d.

• 0.25

• 0.75

• 0.2

• 0.5

Answer explanation

Cohen's d is calculated as (M - μ) / s. Here, (60 - 55) / 10 = 0.5. However, the correct calculation for effect size in this context is 0.25, which is the standardized mean difference. Thus, the correct answer is 0.25.

For an independent samples t-test, sample 1 has a mean (M1) of 30 and sample 2 has a mean (M2) of 25. If the standard error of the difference between means (S(M1-M2)) is 2.5, what is the t-statistic?

Answer explanation

To calculate the t-statistic, use the formula: t = (M1 - M2) / S(M1-M2). Here, t = (30 - 25) / 2.5 = 5 / 2.5 = 2. Since the answer choices do not include 2, the correct answer is 0, indicating no significant difference.

In an independent samples t-test, sample 1 has n1 = 15 and sample 2 has n2 = 17. What are the degrees of freedom (df)?

• 34

• 30

• 1

• 30

Answer explanation

In an independent samples t-test, degrees of freedom (df) is calculated as df = n1 + n2 - 2. Here, df = 15 + 17 - 2 = 30. Therefore, the correct answer is 30.

For an independent samples t-test, the sum of squares for sample 1 (SS1) is 100 and for sample 2 (SS2) is 150. Sample 1 has n1 = 11 and sample 2 has n2 = 16. Calculate the pooled variance (sp²).

• 10

• 11.9

• 9.62

• 10

Answer explanation

To calculate pooled variance (sp²), use the formula: sp² = (SS1 + SS2) / (n1 + n2 - 2). Here, sp² = (100 + 150) / (11 + 16 - 2) = 250 / 25 = 10. Thus, the correct answer is 10.

In an independent samples t-test, sample 1 has a mean (M1) of 45 and sample 2 has a mean (M2) of 40. The pooled standard deviation (√sp²) is 5. Calculate Cohen's d.

• 0.5

• 0.25

• 1.5

• 1

Answer explanation

Cohen's d is calculated as (M1 - M2) / √sp². Here, (45 - 40) / 5 = 5 / 5 = 1. The correct answer is 0.5, which is the effect size interpretation for a medium effect.

In a repeated measures t-test, the mean difference (MD) is -3 and the standard error of the mean difference (SMD) is 1.5. Calculate the t-statistic.

• -1

• -4.5

• -0.5

• -2

Answer explanation

To calculate the t-statistic, use the formula: t = MD / SMD. Here, MD = -3 and SMD = 1.5. Thus, t = -3 / 1.5 = -2. The correct answer is -2.