Question

A primatologist believes that rhesus monkeys possess curiosity. She reasons that, if this is true, then they should prefer novel stimulation to repetitive stimulation. An experiment is conducted in which 12 rhesus monkeys are randomly selected from the university colony and taught to press two bars. Pressing bar 1 always produces the same sound, whereas bar 2 produces a novel sound each time it is pressed. After learning to press the bars, the monkeys are tested for 15 minutes, during which they have free access to both bars. The number of presses on each bar during the 15 minutes is recorded. The resulting data are as follows:

Subject	Bar 1	Bar 2
1	16	31
2	23	26
3	25	40
4	12	24
5	3	22
6	26	27
7	13	28
8	27	39
9	14	26
10	10	18
11	28	36
12	30	32

1.) What is the alternative hypothesis? In this case, assume a nondirectional hypothesis is appropriate because there is insufficient empirical basis to warrant a directional hypothesis.

A.) Rhesus monkeys have a preference for novel stimulation only.

B.) Rhesus monkeys have a preference for repetitive stimulation only.     

C.) In rhesus monkeys there is no difference in preference between novel and repetitive stimulation.

D.) Rhesus monkeys have a preference for either novel stimulation or repetitive stimulation.

2.) What is the null hypothesis?

A.)Rhesus monkeys have a preference for novel stimulation only.

B.) In rhesus monkeys there is no difference in preference between novel and repetitive stimulation.    

C.) Rhesus monkeys have a preference for either novel stimulation or repetitive stimulation.

D.) Rhesus monkeys have a preference for repetitive stimulation only.

3.) Using α = 0.05_2-tail, what is your conclusion?
p(obtained probability) = ______

A.) Reject H₀. Rhesus monkeys appear to prefer novel stimulation.

B.) A conclusion cannot be determined with the given data.     

C.) Reject H₀. Rhesus monkeys appear to prefer repetitive stimulation.

D.) Retain H₀. There is no difference in preference between novel and repetitive stimulation.

4.) What error may you be making by your conclusion in number 3?

A.) You may be making a Type II error, failing to reject H₀ if it is false.

B.) No error; a conclusion cannot be determined with the given data.

C.) You may be making a Type I error, rejecting H₀ if it is true.

D.) You may be making both a Type I error and a Type II error.

5.) To what population does your conclusion apply?

A.) The population is all rhesus monkeys in the United States.

B.) The population is the group of 12 rhesus monkeys that were randomly selected.

C.) The population is the university colony of rhesus monkeys at the time of the experiment.

D.) The population is all rhesus monkeys in the entire world.

Answer 1

1D.) Rhesus monkeys have a preference for either novel stimulation or repetitive stimulation.

2 B)  In rhesus monkeys there is no difference in preference between novel and repetitive stimulation.

Based on the information provided, the significance level is α=0.05, and the degrees of freedom are df=11.

Hence, it is found that the critical value for this two-tailed test is tc​=2.201, for α=0.05 and df=11.

The rejection region for this two-tailed test is R={t:∣t∣>2.201}.

Since it is observed that ∣t∣=6.075>tc =2.201, it is then concluded that the null hypothesis is rejected.

Using the P-value approach: The p-value is p=0.0001, and since p=0.0001<0.05, it is concluded that the null hypothesis is rejected.

4)You may be making a Type I error, rejecting H0 if it is true.

5) The population is the university colony of rhesus monkeys at the time of the experiment.