Question 1

When would you use a one-sample t test rather than a z-test?

Accepted Answer

At test is used when the population standard deviation is not known.

Question 2

Which of the following is NOT needed in order to use the one-sample t test?

Accepted Answer

A)   μ
B)   M
C)   σM
D)   sM C

Question 3

A population has a known mean of 50. A researcher believes that a particular treatment will increase scores and conducts a one-sample t test. What is the null hypothesis?

Accepted Answer

A)   H₀: μ = 50
B)   H₀: μ ≠ 50
C)   H₀: μ ≥ 50
D)   H₀: μ ≤ 50 D

Question 4

Which of the following statements is true regarding the t-distribution?

Accepted Answer

A)   Larger samples make it easier to reject H₀.
B)   Smaller samples make it easier to reject H₀.
C)   Sample size does not affect the ability to reject H₀.
D)   The t-distribution is based on an infinite number of cases.

Question 5

Describe two potential problems which would make the following conclusion problematic: "The medication had no significant effect. Reject H₀, t(32) = +1.92, p > .05."

Accepted Answer

The answer of Describe two potential problems which would make...

Question 6

If the population standard deviation is not known, which statistical test should be used?

Accepted Answer

A)   the z test
B)   the t test
C)   the standard deviation test
D)   the variance test

Question 7

Given a tcrit = -2.08, which of the following obtained t-values will reject H₀?

Accepted Answer

A)   +2.62
B)   -2.10
C)   -1.98
D)   +2.06

Question 8

A researcher is conducting a one-sample t test to see if a particular intervention has any effect on the dependent variable. Alpha is .05 and n = 18. What is tcrit?

Accepted Answer

A)   +1.740
B)   +1.734
C)   ±2.101
D)   ±2.110

Question 9

Given a sample size of 48, the df for a one-sample t test would be _________.

Accepted Answer

A)   46
B)   47
C)   48
D)   49

Question 10

A one-sample t test was conducted which resulted in a significant effect. The sample mean was 95 based on a sample size of n = 25. The population mean was 90 with an estimated standard deviation of 8.42. What was Cohen's d effect size?

Accepted Answer

A)   2.98
B)   -2.98
C)   +.59
D)   -.59

Question 11

In comparison to the normal distribution, as df increase, the t-distribution

Accepted Answer

A)   becomes flatter.
B)   has t-values that extend further into the tails.
C)   becomes increasingly similar in shape to the normal distribution.
D)   is wider that the normal distribution.

Question 12

Given a tcrit = ±2.94, which of the following obtained t-values will reject the H₀?

Accepted Answer

A)   +1.58
B)   -2.58
C)   -3.58
D)   +2.72

Question 13

Which of the following is not one of the assumptions for a one-sample t test?

Accepted Answer

A)   Independent and random selection of subjects.
B)   The dependent variable is normally distributed in the population.
C)   The dependent variable can be measured on an interval or ratio scale.
D)   σ is known.

Question 14

A population has a known mean of 65. A one-sample t test is conducted to determine if a treatment will influence scores on the dependent variable. What is the alternative hypothesis?

Accepted Answer

A)   H₁: μ = 65
B)   H₁: μ ≠ 65
C)   H₁: μ > 65
D)   H₀: μ = 65

Question 15

The population mean on a standardized math test is 75. A tutoring program is implemented at a local college to determine if the math scores would improve as a result. A one-sample t test is conducted. What is the alternative hypothesis?

Accepted Answer

A)   H₁: μ ≥ 75
B)   H₁: μ ≠ 75
C)   H₁: μ > 75
D)   H₀: μ = 75

Question 16

Given s = 8 and n = 32, calculate the standard error of the mean.

Accepted Answer

The answer of Given s = 8 and n =...

Question 17

A population mean is 45. A one-sample t test is conducted with n = 9 subjects and results in a sample mean of 48 with a s = 5. What is tobt?

Accepted Answer

A)   +1.80
B)   -1.80
C)   +5.36
D)   -5.36

Question 18

A new medication shows promising results in reducing the intensity of symptoms in people who suffer from depression. The population mean on a depression inventory is 25. A one-sample t test is administered to a sample of subjects taking the medication. What is the alternative hypothesis?

Accepted Answer

A)   H₁: μ = 25
B)   H₁: μ ≠ 25
C)   H₁: μ 
D)   H₀: μ ≤ 25

Question 19

Determine t_crit for the following situations and decide if H₀ should be rejected. For the one-tailed tests, assume that the researcher is looking for score increases. $\begin{array}{lcccc} &&&\text { One-or Two- }\ &\underline {\text { df } }&\alpha &\underline {\text { Tailed Test }}& t_{\text { obt }}\ a. & 14 &. 01 & \text { One-tailed} & 2.61\ b. &29&.01& \text { Two-tailed} &2.83 \ c. & 5&.05& \text { One-tailed} & 2.20 \ d. &19 &.05 & \text { Two-tailed }&1.98 \ \end{array}$

Accepted Answer

The answer of Determine t_crit for the following situations and...

Question 20

A population has a known mean of 62. A researcher implements a new treatment to a sample to determine if it has an effect on the dependent variable. What is the null hypothesis?

Accepted Answer

A)   H₀: μ = 62
B)   H₀: μ ≠ 62
C)   H₀: μ ≥ 62
D)   H₀: μ ≤ 62

Exam 9: One-Sample T-Test