Hypothesis Testing & ANOVA

1. Grand Strand Family Medical Center is specifically set up to treat minor medical emergencies for visitors to the Myrtle Beach area. There are two facilities, one in the Little River area and the other in Murrels Inlet. The quality assurance department wishes to compare the mean waiting time for patients at the two locations.

Location Waiting time
Little River 31.73 28.77 29.53 22.08 29.47 18.60 32.94 25.18 29.82 26.49
Murrells 22.93 ,23.92,26.92, 27.20, 26.44 ,25.62,30.61,29.44, 23.09, 23.1, 26.69,22.31

At the .05 significance level is there a difference in the mean waiting time?

2. A new computer is sold with innovative flash memory. When compared to computers with conventional memory, the memory of the new machine is clearly faster but initial tests indicate there is more variation in processing time. A sample of 16 computer runs showed that the standard deviation of the processing time was 22 hundredths of a second for the new machine and 12 hundredths of a second for the current machine. At the .05 level of significance can we conclude that there is more variation in the processing time of the new machine? The following is a partial anova table.

source sum of squares df mean square F
Treatment 2
error 20
total 500 11

Complete the table and answer the following questions. Use the .05 significance level.

a. how many treatments are there?
b. what is the total sample size?
c. what is the critical value of F?
d. write out the null hypothesis and the alternate hypothesis.
e. what is your conclusion regarding the null hypothesis?

22. A physician who specializes in weight control has 3 different diets she recommends. As an experiment, she randomly selected 15 patients and then assigned 5 to each diet. After 3 weeks the following weight losses, in pounds were noted. At the .05 significance level, can she conclude that there is a difference in the mean amount of weight loss among the 3 diets?

Plan A Plan B Plan C
5 6 7
7 7 8
4 7 9
5 5 8
4 6 9