ISAT - International Student Admissions Test International Student Admissions Interpreting Scientific Data 1

Question 1

A study comparing two pain medications reports: Drug A reduced pain scores by 18 points (95% CI: 14–22), Drug B reduced pain scores by 15 points (95% CI: 11–19). What can researchers most accurately conclude?

Accepted Answer

The results are inconclusive because the confidence intervals overlap

Answer

Overlapping confidence intervals indicate that the difference between the two drugs may not be statistically significant. When CIs overlap, we cannot confidently conclude one treatment is superior to the other without further testing.

Question 2

Researchers test whether sleep duration affects exam scores. They find r = –0.61 between hours of sleep deprivation and exam performance. Which conclusion is best supported?

Accepted Answer

There is a strong negative association between sleep deprivation and exam scores

Answer

r = –0.61 indicates a moderately strong negative correlation — as sleep deprivation increases, exam scores tend to decrease. Correlation does not imply causation, and r² (not r) gives the proportion of variance explained (~37%).

Question 3

A scatter plot shows the relationship between study hours and test scores for 40 students. The line of best fit has a positive slope, but several data points are widely scattered around the line. What does this pattern suggest?

Accepted Answer

Study hours is a positive but imperfect predictor of test scores

Answer

A positive-sloped best-fit line indicates a positive trend, meaning more study hours is generally associated with higher scores. However, wide scatter around the line shows that study hours alone does not fully predict outcomes — other variables play a role.

Question 4

In a longitudinal study, Group A (n=100) receives a dietary intervention and Group B (n=100) receives no intervention. After 6 months, Group A shows a 5% reduction in cholesterol and Group B shows a 4.8% reduction. The p-value is 0.74. What should the researchers conclude?

Accepted Answer

There is insufficient evidence that the intervention caused a significant difference

Answer

A p-value of 0.74 is far above the conventional threshold of 0.05, meaning the difference between groups is not statistically significant. The minimal difference in outcomes (5% vs 4.8%) combined with the high p-value suggests the intervention may not have a meaningful effect.

Question 5

A table shows bacterial colony counts at three temperatures: 25°C = 340 colonies (SD=45), 35°C = 890 colonies (SD=52), 45°C = 210 colonies (SD=48), with n=20 samples each. Which conclusion is best supported by the data?

Accepted Answer

Bacteria grow best at 35°C, and this difference is likely meaningful given the large gap and small SDs

Answer

The mean at 35°C (890) is dramatically higher than at 25°C (340) or 45°C (210), and the standard deviations (~45–52) are small relative to these differences. This large signal-to-noise ratio strongly suggests the 35°C advantage is a real and meaningful effect.

ISAT - International Student Admissions Test Practice Test

ISAT - International Student Admissions Test Practice Test

ISAT - International Student Admissions Test International Student Admissions Interpreting Scientific Data 1