A Researcher Would Like to Determine If Relaxation Training Will

question 56

Essay

A researcher would like to determine if relaxation training will affect the number of headaches for chronic headache sufferers.For a week prior to training,each participant records the number of headaches suffered.Participants then receive relaxation training and for the week following training the number of headaches is again measured.The data are as follows: $$\begin{array} { l l } \text { Before } & \text { After } \\6 & 4 \\5 & 1 \\3 & 3 \\3 & 1 \\6 & 2 \\2 & 1 \\4 & 3 \\4 & 2 \\\hline\end{array}$$
a. Compute the mean and variance for the sample of difference scores.
b. Do the results indicate a significant difference? Use a two-tailed test with α = .05.
c. Compute Cohen's d to measure the size of the effect.

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Definitions:

Independent Variable

In an experimental setting, the variable that is manipulated by the researcher to observe its effect on the dependent variable.

Double-masked Design

A study design in which neither the participants nor the researchers know who belongs to the control group and who belongs to the experimental group, minimizing bias.

Experimenter Expectancies

The potential influence that a researcher's beliefs, hopes, or biases can have on the outcome of an experiment, often impacting the behavior being studied.

Rosenthal Effect

The phenomenon in which the higher expectations placed upon individuals either by themselves or others lead to better performance; also known as the Pygmalion effect.