Question

An experimenter interested in the causes of headaches suspects that much of the discomfort people suffer is from muscle tension. She believes that if people could relax the muscles in the head and neck region, the pain of a headache would decrease. Nine subjects are randomly selected from a headache pain clinic and asked to keep track of the number of headaches experienced over a two week period (baseline measurement). The subjects then completed a 6-week seminar in biofeedback training to learn how to relax the muscles in their head and neck. After completing the seminar, the subjects were then asked to record the number of headaches they experienced over a two week period using their new biofeedback skills. The number of headaches reported by subjects before and after the biofeedback training seminar are reported below.

Before Seminar: 17 13 6 5 5 10 8 6 7

After Seminar: 3 7 2 3 6 2 1 0 2

a. Describe (1) the independent variable and its levels, and (2) the dependent variable and its scale of measurement.

b. Describe the null and alternative hypotheses for the study described.

c. Using Excel, conduct a statistical test of the null hypothesis at p = .05. Be sure to properly state your statistical conclusion.

d. Provide an interpretation of your statistical conclusion in part C.

e. What type of statistical error might you have made in part C?

f. Obtain the 95% confidence interval using the obtained statistic.

g. Provide an interpretation of the confidence interval obtained in part f.

h. Does the confidence interval obtained support your statistical conclusion? Explain your answer.

Answer 1

Answer a :

Independent dependent variable : An independent variable is the variable of the experiment that the dependent variable depends on. For example, in an experiment testing the effects of soil quality on a plant's growth, the dependent variable would be the plant's growth and the independent variable would be the quality of the soil.

So the two variable are not depend to each other called as independent variable otherwise called as dependent variable.

Measurements of scales :

1) Nominal scale : It consist of classified the given object in two or more categories.

2) Ordinal Scale: It consist classified the object into two or more groups by using certain order.

3)Interval Scale : It consist of classified the object with equal measurements but the zero point is arbitary.

4) Ratio Scale : It consist of classified object with equal measurements.

Answer b ) : Here we have to given the data before and after (that means dependent )so we use the paired t test.

Answer d : So P-value = 0.003471

We can conclude the decision on the basis of p-value.

Rule : If p-value is less or equal to level of significance(p=0.05) then reject the null hypothesis.

If p-value is greater than level of significance (p=0.05) then fail to reject the null hypothesis.

So here p-value is less that level of significance that means we reject the null hypothesis.