People who have a positive attitude tend to be happier than those who have a negative or pessimistic attitude. A psychologist conducts an experiment to explore this relationship. He randomly selects 50 participants. He randomly divides those participants into two groups of 25. In one group, the participants are instructed to write down three positive statements each day. The members of the other group just go through their days as normal. After 3 weeks, the treatment group's happiness increased from an initial average of 7 to an average of 9 on a scale of 1 to 10. The control group's happiness average decreased from 7 to 5 on the same scale. (a) What is the independent variable in this study?
writing positive statements or not
happiness the 50 participants
the 25 participants
(b) What is the dependent variable in this study?
writing positive statements or not
happiness
the 50 participants the 25 participants
(c) Suppose the parameter we wish to estimate is the mean increase (or decrease) in happiness (after the study minus before the study).
For the treatment group, identify the point estimate. For the treatment group, calculate the margin of error of the point estimate. Assume that s = 1.2 and use a confidence level of 90%. (Use a table or technology. Round your answer to three decimal places.)