A dietitian wishes to compare the effect of mineral supplements on the cholesterol levels of his patients.
Question:
A dietitian wishes to compare the effect of mineral supplements on the cholesterol levels of his patients. Six randomly selected patients were pretested for cholesterol and given mineral supplement for 6 weeks and then tested for cholesterol. The results are given below:
subject | 1 | 2 | 3 | 4 | 5 | 6 |
Before | 220 | 215 | 248 | 180 | 192 | 344 |
After | 210 | 180 | 220 | 178 | 183 | 328 |
a. Find the differences in the cholesterol levels, Di's and compute the mean, XDbar
and the std. deviation, SD of the differences
b. Construct a box-plot for the differences and comment on the result
c. Find a 95% confidence interval estimate for D (difference in the true mean cholesterol levels before and after the mineral supplement)
d. Is there sample evidence to conclude that the mineral supplement reduces the cholesterol level? Test at =0.05; write the hypotheses, compute the test statistic & P-value, make a decision, and write a summary
2. Write about the sampling distribution of the mean of the differences, XDbar
mentioning all essential points