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Biostatistics Knowledge Center

Educational articles on statistical methods, SPSS usage, and academic research.

Category:All(6 articles)

Planning for Participant Attrition: Correct Inflation and Missing-Data Strategy

Incorporate attrition using the correct formula, timing, causes and analysis strategy rather than adding a percentage mechanically.

What Happens to Power with More Groups? Contrast-Focused Sample Planning

Link sample-size planning for ANOVA, planned contrasts, unequal allocation and multiplicity to the actual primary hypothesis.

The Target Effect Behind Sample Size: From Clinical Rationale to Assumption

Choose a target effect using clinical importance, external evidence and sensitivity scenarios rather than automatic Cohen thresholds.

Why Observed Power Cannot Explain a Non-Significant Result

Observed power largely restates the p value. Use effect estimates, confidence intervals and prospective planning after a non-significant result.

Determining Sample Size in Prevalence Studies

Determining Sample Size in Prevalence Studies

Prevalence refers to the frequency with which a disease or event occurs in a population. It is usually obtained from cross-sectional studies.

Sample Size for Correlation Coefficient (Relationship)

Sample Size for Correlation Coefficient (Relationship)

It is used to examine the relationship between clinical variables and scales, and between clinical variables and measurements such as age and operation duration.