Question

What sort of SEM for BMI would you expect if the analyst in (2) obtained a sample size of n=400 instead of n=100?

Selected Answer:

a.

0.50

Answers:

a.

0.50

b.

1.50

c.

2.25

d.

0.75

The analyst in (2) decides to define obesity as having a BMI > 30. If there were 25 subjects with BMI > 30, what is the estimated standard error associated with the sample proportion of obese subjects?

Selected Answer:	d. 0.0433
Answers:	a. 3.1315
	b. 0.7560
	c. 2.5000
	d. 0.0433

Statistical analyst obtains BMI measurements for n=100 subjects and calculates the standard error of the mean (SEM) as 1.00. What is the sample standard deviation for BMI in this data set?

Selected Answer:	a. 10.0
Answers:	a. 10.0
	b. 5.0
	c. 12.3
	d. 20.0

What is the upper limit for a 95% confidence interval for the proportion obese in (4)?

A. 0.33

B. 0.13

C. 0.25

D. 37.43%

The analyst in (2) decides to define obesity as having a BMI > 30. If there were 25 subjects with BMI > 30, what is the estimated standard error associated with the sample proportion of obese subjects?

Selected Answer:	d. 0.0433
Answers:	a. 3.1315
	b. 0.7560
	c. 2.5000
	d. 0.0433

Answer 1

From the given information,

1.

SEM= Sample standard deviation/Squareroot(n)= 10/Squareroot(400)=10/20=0.5

Hence, Option a. is correct.

2. Estimated standard error = Squareroot((p*(1-p))/n) =Squareroot((0.25*(1-0.25))/100)=0.0433

Hence, Option d. is correct.

3. Sample standard deviation= Squareroot(n)*SEM = Squareroot(100)*1=10*1=10

Hence, Option a. is correct.

4. Upper Limit= p + 1.96*SEM = 0.25 + 1.96*0.0433 = 0.25 + 0.08 = 0.33

Hence, Option A. is correct.

5. Estimated standard error = Squareroot((p*(1-p))/n) =Squareroot((0.25*(1-0.25))/100)=0.0433

Hence, Option d. is correct.