1.2, 1.5, 1.6, 1.8, 1.12, 1.14, 2.2, 2.6, 2.10, 2.12, 2.14, 2.16, 3.1, 3.8, 3.14, 3.18, 3.32, 3.48
Answers to homework problem set #1:
1.2) a.) true; b.) true; c.) false; d.) false;
1.5) a.) A type I error would be to assume that the gun is not loaded when it is. A type II error would be to assume that the gun is loaded when it is not. A type I error is more severe in this case.
b.) A type I error would be to assume that the dog doesn�t bite when it in fact does. A type II error would be to assume that the dog does bite when in fact it doesn�t. A Type I error would be more serious.
c.) A type I error would be to assume that the mall is closed when it is open. A type II error would be to assume that the mall is open when it is closed. A type II error would be more serious.
d.) A type I error would be concluding that the watch is waterproof when it isn�t. A type II error would be to conclude that the watch isn�t waterproof when it is. A type I error would be more serious.
1.6) a.) Type I error,
b.) Type I error,
c.) Type I error,
d.) Type II error
1.8) Ho: not a drug user;
H1: is a drug user
a.) A type I error would be to assume that he is a drug user when he is not and a type II error would be to assume that he is not a drug user when in fact he is.
b.) Since the test classifies the person as a drug user 4% of the time when the person is not a drug user, the chance of a type I error is 4%.
1.12) a.) Ho: that the new drug Septaphine is the same or worse at reducing blood pressure than Cephaline.
H1: that the new drug is better at reducing blood pressure.
b.) The alternative hypothesis was accepted.
c.) Yes, a mistake could have been made, a Type I error that is. It could be assumed that the drug is better when in fact it is not better at reducing blood pressure.
1.14) The answer is e.) Both answers b and c are correct.
2.2) b.) a statistic.
2.6) c.) the percent of defective items in the sample is 2.5%.
2.10) a.) sample-statistic.
b.) Non-response bias.
2.12) selection bias but also other answers were accepted as long as you supported your answer.
2.14) a.) i selection bias;
b.) ii non-response bias;
c.) iii response bias.
2.16) c.) any two samples of the same size will have the same chance of being drawn.
3.1) a.) explanatory variable is number of ounces of coffee and the response is exam performance
b.) explanatory variable is counseling per week and the response is grade point average
c.) explanatory variable is number of roommates assigned to and the response is physical health
d.) explanatory variable was the fact that people were told they were a good or bad driver and the response is reaction time.
3.8) a.) Observational or prospective study
b.) response variable: heart disease status
explanatory variale: amount of stick margarine in diet
3.14) a.) progress status; success rate
b.) teacher and method of teaching
c.) 5 * 4 * 3 = 120
3.18) a.) number of apple per tree
b.) type of fertilizer and soil moisture status
c.) 3 levels of type of fertilizer and 2 levels of soil moisture
d.) 18
3.32) a.) ii.) Explanatory variable
b.) i.) response variable
c.) iv.) a retrospective observational study
3.48) a.) reaction time to stimulus
b.) yes, since more than one person was assigned to each group.
d.) 0.50 or 50%
e.) H1
f.) p-value is less than 0.05 because the data was statistically significant.
g.) an error can always occur. A type I or Type II error could have been made.