Research Methodology & Design Flashcards

Allocation concealment in a randomized trial primarily prevents:

Answer: Selection bias at enrollment

Concealing the upcoming assignment stops recruiters from steering certain patients into specific arms.

An intention-to-treat analysis includes participants:

Answer: In the group to which they were randomized, regardless of adherence

ITT analyzes everyone as randomized, preserving the benefits of randomization.

Block randomization is mainly used to:

Answer: Keep group sizes balanced throughout enrollment

Blocks ensure equal (or set-ratio) allocation at regular intervals during recruitment.

Stratified randomization helps ensure that:

Answer: Important prognostic factors are balanced across arms

Randomizing within strata (e.g., sex, site) balances key covariates between groups.

A non-inferiority trial aims to show that a new treatment is:

Answer: Not worse than the standard by more than a prespecified margin

Non-inferiority designs test whether a new therapy falls within an acceptable margin of the active comparator.

In a double-blind trial, who is unaware of treatment assignment?

Answer: Both participants and the investigators assessing them

Double-blinding keeps both participants and investigators/outcome assessors unaware of allocation.

Which approach is used when a placebo would be unethical because effective treatment exists?

Answer: Active-control comparison

Comparing against an established active treatment avoids denying patients known effective care.