Question

In a study evaluating the impact of a healthy diet on energy levels among office workers, 60 workers who reported low energy levels were recruited. What treatment assignments could be used in this study?

Answer 1

You could assign treatments in several reasonable ways depending on the study question and resources. Common options:

1. Two-arm randomized controlled trial (most straightforward)
- Randomly assign the 60 workers to:
- Healthy-diet intervention (n = 30)
- Control (usual diet or attention control, n = 30)
- Randomization can be simple or blocked to keep group sizes equal.

2. Stratified randomization
- If you want to balance important baseline factors (e.g., baseline energy score, age, sex), stratify on those and then randomize within strata (still typically 30/30 overall).

3. Matched-pairs randomization
- Pair workers with similar baseline characteristics and energy scores, then randomize one of each pair to diet and the other to control.

4. Cross-over design
- Split into two sequences (each n = 30): Sequence A = healthy diet then usual diet; Sequence B = usual diet then healthy diet, with a washout period. Each person serves as their own control.

5. Multiple-arm trial (compare different diets or intensities)
- e.g., three groups of 20: Mediterranean-style healthy diet, low-carb healthy diet, usual diet control.

6. Cluster randomization (if intervention delivered by team/office)
- Randomize whole teams or offices to diet vs control (useful if contamination between coworkers is a concern).

Other practical considerations: include an attention/placebo control (diet counseling without actual diet change) to control for placebo effects; use a waitlist control for ethics (offer the intervention after study); and pre-specify primary outcome timing and washout length for cross-over designs.

If you want a single recommendation: use a randomized two-arm design with 30 in the healthy-diet group and 30 in the control group, stratified by baseline energy level.