ABP Biostatistics and Evidence-Based Literature Appraisal 2

Question 1

A periodontal RCT reports 20% of control patients and 10% of test patients had recurrent pocket depth ≥5 mm. What is the number needed to treat (NNT)?

Accepted Answer

10

Answer

ARR = 20% − 10% = 10%, so NNT = 1/0.10 = 10.

Question 2

A 95% confidence interval for a mean attachment gain difference is −0.2 to 1.4 mm. What can be concluded at α = 0.05?

Accepted Answer

The difference is not statistically significant

Answer

The interval includes 0 (no difference), so the result is not statistically significant.

Question 3

Which test is most appropriate to compare mean probing depth reduction among three independent treatment groups with normally distributed data?

Accepted Answer

One-way ANOVA

Answer

One-way ANOVA compares means across three or more independent groups.

Question 4

In a split-mouth design for evaluating a graft material, which analysis is generally appropriate?

Accepted Answer

Paired analysis accounting for within-patient correlation

Answer

Sites within the same patient are correlated, so paired or mixed-model analysis is needed.

Question 5

What is the main purpose of intention-to-treat (ITT) analysis?

Accepted Answer

To preserve randomization and reduce attrition bias

Answer

ITT analyzes participants in the groups to which they were randomized, preserving the balance achieved by randomization.

(ABP) American Board of Periodontology Practice Test

(ABP) American Board of Periodontology Practice Test

ABP Biostatistics and Evidence-Based Literature Appraisal 2