Research Methods in the Health Sciences

here are several free and widely used software programs that can help you calculate sample sizes for research studies. Here are some of the best options:

G*Power:

1. • G*Power is a user-friendly and powerful software tool for calculating sample sizes and performing power analyses for various statistical tests. It covers a wide range of statistical tests and research designs and is available for both Windows and macOS.
   • Website: http://www.gpower.hhu.de/

OpenEpi:

1. • OpenEpi is an open-source epidemiologic calculator that provides sample size calculations and other epidemiological tools. It's a web-based tool, so you can access it from any device with internet connectivity.
   • Website: http://www.openepi.com/

PS Power and Sample Size Calculator:

1. • PS is a free and user-friendly software tool for sample size and power calculations. It supports a wide range of study designs and statistical tests. It's available for Windows and macOS.
   • Website: https://www.ps-power.sourceforge.io/

Epi Info:

1. • Epi Info is a free suite of software tools for epidemiologists and public health professionals. It includes a sample size calculator along with other epidemiological features. It's available for Windows and mobile devices.
   • Website: https://www.cdc.gov/epiinfo/index.html

SamplePower:

1. • SamplePower is a free sample size and power analysis software provided by IBM. It's part of the IBM SPSS Statistics suite but can be used independently for sample size calculations. It's available for Windows.
   • Website: https://www.ibm.com/analytics/spss-statistics-software

Sample Size Calculator by Creative Research Systems:

1. • This web-based tool provides a straightforward interface for calculating sample sizes for surveys and polls. It's suitable for basic sample size calculations.
   • Website: https://www.surveysystem.com/sample-size-formula.htm

DSS Research Calculator:

• DSS Research provides a web-based sample size calculator that covers a variety of survey and research scenarios. It's user-friendly and can be accessed online.
• Website: https://www.dssresearch.com/KnowledgeCenter/toolkitcalculators/samplesizecalculators.aspx

Sample Size Calculator by Raosoft:

• Raosoft offers a free online sample size calculator for surveys and research. It's a simple tool for basic sample size calculations.
• Website: http://www.raosoft.com/samplesize.html

When choosing a sample size calculator, consider the specific statistical tests and study designs you'll be working with, as well as the user interface and ease of use. These free tools can be valuable resources for researchers and professionals who need to determine the appropriate sample size for their studies.