# Research: Sampling and Null Hypothesis

Topics: Sampling, Null hypothesis, Epidemiology Pages: 26 (5622 words) Published: May 9, 2013
COMMED FINAL EXAM 2012

A new drug is to be compared to Metronidazole if it is better with respect to cure rate of amoebiasis in a randomized clinical trial. The new drug will be considered better than Metronidazole if it shows a 5% difference from the cure rate of 80%. The researcher desires an 80% power and a 95% confidence.

1. The determination of the sample size will be based on
a. estimation of a population mean
b. hypothesis testing between two proportions
c. estimation of a population mean
d. hypothesis testing between two means

RATIONALE: First, check muna if what they’re looking for is mean or proportions. I’m not really sure, but technique ko dyan, pag may mga decimal point, MEAN YUN. Mostly, ang mga MEAN cases ay yung mga blood pressure (systole, diastole). So in this case, you’re just comparing two drugs. Hence, proportions. Also, hypothesis palagi for sample size.

2. What is the null hypothesis?
a. the cure rate in the new drug is not equal to the cure rate in Metronidazole b. the cure rate in the new drug is better than the cure rate in Metronidazole c. the cure rate in the new drug is equal to the cure rate in Metronidazole d. the cure rate in the new drug is not better to the cure rate in Metronidazole RATIONALE:

Null Hypothesis (Ho) = no change/equal
Alternative Hypothesis (Ha) = with change/not equal
**PLEASE PLEASE PLEASE memorize!! Also, be careful with this. Always read the case first. The hypothesis will always depend on the case. Here kasi, they’re comparing the efficacy of 2 drugs to treat amoebiasis. Hence, ang NULL ay equal sila ng efficacy.

3. In the determination of the sample size in this study, you will utilize a: a. One-tailed test – relationship in one direction only b. Two-tailed test - testing for the possibility of a relationship in both directions c. Either A or B

d. Both A and B
RATIONALE:
Kaya one tailed, kasi tinitingnan lang naman sa case if effective ang new drug to treat amoebiasis and not amoebiasis new drug. Gets ba?

4. The new drug showed an 8% difference in cure rate from Metronidazole with a 95% confidence interval of 2-14%. Your decision will be to: a. Reject the alternative hypothesis
b. Fail to reject the alternative hypothesis
c. reject the null hypothesis
d. Fail to reject the null hypothesis
RATIONALE:
Sabi sa case na kapag may 5% difference siya from the cure rate of Metronidazole, effective siya. In this case, 8% na siya which means EFFECTIVE! Therefore, what you should do is to REJECT THE NULL HYPOTHESIS (which is both drugs are equal). Gets?

What if 4% lang? eh di ang answer ay dapat fail to reject the null hypothesis which means na you ACCEPT the null hypothesis.. You accept that both drugs are equal.
I know, ang arte. Pero ganon talaga. Fail to reject and reject ang drama nitong commed. And, your basis is always the null hypothesis.

5. The new drug was found to have a cure rate of 88%. Your conclusion would be: a. There is sufficient evidence at the 0.05 level of significance to reject the claim that the cure rate in the new drug is equal to the cure rate in Metronidazole. b. There is insufficient evidence at the 0.05 level of significance to reject the claim that the cure rate in the new drug is equal to the cure rate in Metronidazole. c. There is sufficient evidence at the 0.05 level of significance to support the claim that the cure rate in the new drug is equal to the cure rate in Metronidazole. d. There is insufficient evidence at the 0.05 level of significance to support the claim that the cure rate in the new drug is equal to the cure rate in Metronidazole. RATIONALE:

The conclusion is always written this way: “There is SUFFICIENT/INSUFFICIENT evidence at the 0.05 level of significance to REJECT the claim that the cure rate in the new drug is equal to the cure rate in Metronidazole”

Kaya A, kasi the case says na if nag 85% yung...