ISAT - International Student Admissions Interpreting Scientific Data 2

Question 1

A clinical trial: treatment group (250) shows 15% recovery, control group (250) shows 12% recovery. P-value is 0.23. What should researchers conclude?

Accepted Answer

The difference is not statistically significant (p > 0.05), so the difference may be due to chance

Answer

The drug is effective

Answer

The drug is ineffective and should be abandoned

Answer

Sample size was too small

Question 2

Plant growth under three light conditions: Red=12.4cm (SD=2.1), Blue=15.8cm (SD=1.9), White=14.2cm (SD=2.3), n=30 each. Which comparison is most likely statistically significant?

Accepted Answer

Red vs Blue

Answer

Red vs White

Answer

Blue vs White

Answer

None

Question 3

Ice cream sales and drowning deaths are strongly correlated (r=0.92). What is the most appropriate interpretation?

Accepted Answer

A confounding variable (temperature/season) drives both independently

Answer

Ice cream causes drowning

Answer

Drowning causes ice cream purchases

Answer

Statistical error

Question 4

A vaccine is 90% effective. In 10,000 people (5,000 vaccinated, 5,000 not), 50 unvaccinated get the disease. How many vaccinated people would get it?

Accepted Answer

5

Answer

10

Answer

0

Answer

45

Question 5

Regression: y = 3.2x + 42 (x=study hours, y=score). A student studies 12 hours. What does the model predict, and what does the y-intercept mean?

Accepted Answer

80.4; the predicted baseline score with zero study hours

Answer

80.4; the average student's score

Answer

38.4; minimum possible score

Answer

80.4; maximum possible score

Question 6

Treated mice (n=100): 30 developed tumors. Control (n=100): 45 developed tumors. Calculate relative risk reduction and absolute risk reduction.

Accepted Answer

RRR=33.3%, ARR=15%

Answer

RRR=15%, ARR=33.3%

Answer

RRR=30%, ARR=45%

Answer

RRR=66.7%, ARR=30%