week 3 problems

Week 3 Problems—30 points

10 points per problem. Put answers in the table:

1. RD = .366-.175 = .175 RR= = = 2.09 OR == = 2.73 Upper Limit of CI – 1.61 Lower Limit of CI – 0.41 Based om the Confidence Interval values which of the following are true? Answer: D – One can be 95% confident that the true value will be greater than both the upper and lower limits

2.

3.

1. A clinical trial is conducted comparing a new pain medication for arthritis. Participants are randomly assigned to receive the new medication or a placebo. The outcome is pain relief within 30 minutes. The data are shown below.

	Pain Relief	No Pain Relief
New Medication	44	76
Placebo	21	99

Estimate the risk difference in pain relief between treatments

=

Estimate the relative risk in pain relief between treatments

=

Estimate the odds ratio in pain relief between treatments

=

The upper and lower limits of the are shown below

Lower Limit of CI: ____0.41____

Upper Limit of CI: ___1.61_____

Based on the Confidence Interval values which of the following are true?

A. One can be 95% confident that the true value will be greater than the upper limit.

B. One can be 95% confident that the true value will be greater than the lower limit.

C. One can be 95% confident that the true value will between the upper and lower limit.

D. a and b

2.The following data were collected in a clinical trial evaluating a new compound designed to improve wound healing in trauma patients. The new compound is compared against a placebo. After treatment for 5 days with the new compound or placebo the extent of wound healing is measured and the data are shown below.

	Percent Wound Healing
Treatment	0-25%	26-50%	51-75%	76-100%
New Compound (n=125)	15	37	32	41
Placebo (n=125)	36	45	34	10

Is there a difference in the extent of wound healing by treatment? (Hint: Are treatment and the percent wound healing independent?) Run the appropriate test at a 5% level of significance.

df= ________

alpha= ________

Reject H₀if?²_> ________

Compute expected frequencies

Expected Frequency = (Row Total * Column Total)/N.

Complete the expected frequencies for each cell.

	Percent Wound Healing	Total
Treatment	0-25%	26-50%	51-75%	76-100%
New Compound	15 ( )	37 ( )	32 ( )	41 ( )	125
Placebo	36 ( )	45 ( )	34 ( )	10 ( )	125
Total	51	82	66	51	250

Compute ?².

?²₌ ________

Based on comparing the computed ?²to the rejection level ?²which of the following is (are) true?

A. We have statistically significant evidence at alpha=0.05 to show that H₀ is false.

B. Treatment and percent wound healing are not independent.

C. Treatment and percent wound healing are independent.

D. a and b.

3. A clinical trial is conducted comparing a new pain reliever for arthritis to a placebo. Participants are randomly assigned to receive the new treatment or a placebo and the outcome is pain relief within 30 minutes. The data are shown below.

	Pain Relief	No Pain Relief
New Medication	44	76
Placebo	21	99

Is there a significant difference in the proportions of patients reporting pain relief? Run the test at a 5% level of significance.

Reject H₀ if Z < ________ or if Z >________

alpha= ________

⁼________

⁼________

= ________

Z =________

Based on comparing the computed zto the rejection level zwhich of the following is (are) true?

A. We have statistically significant evidence at alpha=0.05 to show that H₀ is false.

B. We have statistically significant evidence at alpha=0.05 to show thatthere a significant difference in the proportions of patients reporting pain relief.

C. We do not have statistically significant evidence at alpha=0.05 to showthere a significant difference in the proportions of patients reporting pain relief.

D. a and b