How many repetitions under a given treatment or condition are required to establish a baseline

Sample Solution

1. Variability of the measurement: If the measurement is highly variable (e.g., heart rate), more repetitions may be needed to establish a reliable baseline.
2. Desired level of precision: A higher level of precision requires more repetitions.
3. Practical constraints: Time, resources, and participant availability can limit the number of repetitions possible.
4. Nature of the intervention: Some interventions may require a longer baseline period to assess the natural variation of the outcome measure.
5. Statistical power: The desired level of statistical power in subsequent analyses can influence the required sample size, including the number of baseline measurements.

• At least 3-5 repetitions: This is a common starting point for many studies.
• Stability analysis: Examine the data for stability. If the measurements are consistent across repetitions, a smaller number might suffice.
• Pilot studies: Conducting a small-scale pilot study can help determine the optimal number of repetitions for a specific study.

• Baseline period: The duration of the baseline period (time between repetitions) is also important. Sufficient time should be allowed for physiological recovery or to minimize carryover effects from previous measurements.
• Data analysis: The choice of statistical analysis method can influence the interpretation of baseline data.