EXPERIMENT 1:

A physiologist has conducted an experiment to examine the effects of a newly discovered hormone (called hormone X) on aggression. Ten rats were injected with hormone X, and 10 other rats received a placebo injection (the control group). The number of aggressive behaviors was counted for each rat in the study.

The following results were obtained:

• Hormone X Group: Mean aggressive behaviors = 8.4, s = 1, n = 10
• Control (placebo) Group: Mean aggressive behaviors = 5.6, s = 1.2, n = 10
• We will use = .05, two-tailed test

What type of t- test should be used?

Group of answer choices

Repeated measures (i.e., paired samples)t-test

Independent samplest-test

Z test

correlation

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For the above experiment 1 (on aggression in rats), the null hypothesis in appropriate statistical notation is: _D = 0

Group of answer choices

True

False

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For the above experiment 1 (on aggression in rats), use the information provided above and consult the appropriate degrees of freedom (df) formula on the supplemental material. What are the degrees of freedom for this experiment?

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For the above experiment 1 (on aggression in rats), given the df you calculated, what is the critical value, for a two-tailed test? (use the table provided in the supplemental material; be sure to list 3 decimal places out, like you see in the table)

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For experiment 1 (on aggression in rats), what is the standard error for the t statistic (i.e., the bottom part of the t formula)? Remember the formula for calculating this has been provided in the supplemental material.

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For experiment 1 (on aggression in rats), compute the t. What is the t-statistic that you obtained? Remember the formula has been provided in the supplemental material.

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For experiment 1 (on aggression in rats), should the null hypothesis be accepted or rejected?

Group of answer choices

Rejected

Accepted

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Which option most accurately describes the findings from experiment 1 (on aggression in rats)? Hint: look at your decision to the above question along with the means

Group of answer choices

Hormone X group had more aggressive behaviors than the control group.

There is no difference between Hormone X and the control group on number of aggressive behaviors.

Control group had more aggressive behaviors than the hormone X group.

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