Practical guide to calculate sample size for chi-square test in biomedical research

In biomedical research, the calculation of sample size is a critical component of study design. Adequate sample size ensures the reliability of statistical tests, including the chi-square test. This manuscript outlines the use of an online sample size calculator for chi-square tests. The paper includes detailed explanations of the formulas used in the calculations and highlights the importance of power analysis in planning research studies. This tool is designed to assist and guide researchers in determining the optimal sample size for detecting statistically significant differences in categorical data. We describe the theory behind the chi-square test, the statistical principles involved in sample size calculation, and the specific methodology for using the sample size calculator. The calculator is freely available to use at https://hanif-shiny.shinyapps.io/chi-sq/ .