Question

Statistics Exam 2 (1) Compatibility Mode Layout References Mailings ReviewView HelpTell me what you want to do A-e. A.|ー 1,-. Isa-B. ||1Normal 1No Spac Heading 1 Heading 2 Title Paragraph Styles a matched-subjects design d. all of the above would require the same number of subjects 22. For an experiment comparing two treatment conditions, an independent-measures design would obtain score(s) for each subject and a repeated-measures design would obtainscore(s) for each subject a. 1, 1 b. 1,2 c. 2,1 d. 2,2 23. A researcher reports a t statistic with df- 24 from a repeated-measures research study. How many subjects participated in the study? a. n=11 b. n- 13 c. n=23 d. n 25 24. An advantage of a repeated-measured design (compared to an independent-measures design) is that it reduces the contribution of error variability due to b. degrees of freedom c. the effect of the treatment d.

Answer 1

22) For an experiment comparing two treatment conditions, an independent measure design would obtain --- score for each subject and repeated measure design would obtain --- scores for each subject.

ANSWER: Option (c) 2,1

Because repeated measures design is used when same subjects participate in both conditions of the experiment. And independent measure design is used when we have two different groups of subjects, one group performing one condition in the experiment, and the other group performing the other condition.

23) A researcher reports a t statistic with df=24 from a repeated measures research study. How many subjects participated in the study.

ANSWER: Option (d) n=25

Because the degrees of freedom for repeated measures t test is number of observations-1 (i.e. $n-1$).

Thus $n-1=24$$\Rightarrow n=25$

Thus number of subjects participated in the study is $25$.

24) An advantage of repeated measures design (compared to an independent measures design) is that it reduces the contribution of error variability due to ---

ANSWER: Option (d) individual differences error

Because as is the case with repeated measures designs we can partition out variability due to individual differences.

In a between-subjects design there is an element of variance due to individual difference that is combined with the treatment and error terms:

$SS_{Total}=SS_{Treatment}+SS_{Error}$

The primary advantage of the repeated measures design is to use experimental control to reduce one or more sources of error variability.

2) The null hypothesis

ANSWER: Option (a) states that the treatment has no effect.

According to the null hypothesis, the population mean after treatment is the same is it was before treatment.

3) The critical region for a hypothesis test consists of ---

ANSWER: Option (a) Outcomes that have a very low probability if the null hypothesis is true

The critical region consists of outcomes that are very unlikely to occur if the null hypothesis is true. That is, the critical region is defined by sample means that are almost impossible to obtain if the treatment has no effect.

4) In general, changing the alpha level from 0.01 to 0.05 will ---

ANSWER: Option (a) increase the likelihood of rejecting the null hypothesis.

With an alpha level of 0.01, there will be only a 1% chance of rejecting a true Ho. The change in alpha will also effect the Type II error, in the opposite direction. Increasing alpha from 0.01 to 0.05 decreases the chance of a Type II error (increase the likelihood of rejecting the null hypothesis).

7) The type I error is

ANSWER: Option (b) Rejecting a true null hypothesis

Rejecting the null hypothesis when it is true is called a Type I error.

8) A type II error means that a researcher has ---

ANSWER: Option (c) falsely concluded that a treatment has no effect

Type II error occurs when one fails to reject a null hypothesis that is actually false (That is fails to reject false null hypothesis). Thus researcher has falsely concluded the null hypothesis that a treatment has no effect.

9) Which of the following is the fundamental difference between t statistic and a z score?

ANSWER: Option (d) All of the above are differences between t and z.

10) Which of the following terms are not required when using t statistic?

ANSWER: Option (b) $\mu$

As t statistic requires sample size (n), Degrees of freedom and sample standard deviation.