BESC 3010 Chpt 9
A two-sample t-test is an appropriate test when..
two samples are being compared on an interval or ratio level variable.
When the means of two groups are the same, then Cohen's d...
will equal 0.
If n = ∞, then what is the critical value of t for alpha = .05?
±1.96
If a research conducts an inferential test (such as a t-test) and rejects the null hypothesis, then what is the probability of a Type II error?
0.00
If a research conducts an inferential test (such as a t-test) and retains (i.e., fails to reject) the null hypothesis, then what is the probability of a Type I error?
0.00
If you conduct an inferential test and retain the null hypothesis, then what is the chance of a Type I error?
0.00
If a researcher wants to compare the effects of an antidepressant to the effects of a placebo on levels of anxiety, then what is the dependent variable (that is, the DV)?
Levels of anxiety
If a researcher wants to compare the effects of an antidepressant to the effects of a placebo on levels of anxiety, then what is the grouping variable?
Medication: antidepressant vs. placebo
If a researcher wants to compare the effects of an antidepressant to the effects of a placebo on levels of anxiety, then what is the independent variable (that is, the IV)?
Medication: antidepressant vs. placebo
Imagine that a researcher conducts a repeated measures t-test with critical values of ±2.78 and gets an observed value (or test value) of t = -3.30. What is the proper conclusion in this case?
Reject the null hypothesis
If you conduct a one-tailed (i.e., directional) two-sample t-test with a critical value of +2.20 and gets an observed value of t = -3.53, then what should you do?
Retain the null hypothesis
Imagine that a researcher conducts a one-tailed (i.e., directional) two-sample t-test with a critical value of -1.83 and gets an observed value (or test value) of t = +1.98. What is the proper conclusion in this case?
Retain the null hypothesis
Imagine that a researcher conducts a two-sample t-test with critical values of ±2.10 and gets an observed value (or test value) of t = 1.98. What is the proper conclusion in this case?
Retain the null hypothesis
Imagine that you conduct a two-sample t-test with critical values of ±2.30 and gets an observed value (or test value) of t = -2.09. What should you do?
Retain the null hypothesis
If you conducted an experiment to compare the effects of two different online ad campaigns on the number of clickthroughs (i.e., how often people clicked on each ad), then what is the dependent variable (DV)?
The number of clickthroughs
Which inferential test should be used to compare two sample means to each other?
The two-sample t-test
If a researcher gathers data from participants before and after they participate in an exercise training program and wants to know whether their performance scores improved, then he should use...
a one-tailed, repeated measures t-test.
If you want to compare the means of two different groups to each other then you should use...
a two-sample t-test.
As the means of two groups become more similar, Cohen's d will...
approach 0.
The comparison group in a repeated-measures t-test is...
each person's own score at time 1
The comparison group in a repeated measures t-test is...
each person's own score at time 1.
The most important difference between Cohen's d and the t-test is that Cohen's d...
is not affected by sample size.
What is the formula for the degrees of freedom (df) for a two-sample t-test?
n - 2
If a researcher conducts a t-test with an alpha of .01 and gets a p-value of .25, then the researcher should...
retain (i.e, fail to reject) the null hypothesis.
Cohen's d indicates the number of...
standard deviations between two means.
When the means of two samples are being compared and Cohen's d = 1.10, then...
the means are 1.1 standard deviations apart.
When the means of two samples are being compared and Cohen's d = 0, then...
the means are identical.
One assumption of the two-sample t-test is that...
the two samples are independent of one another.
