Determination of sample size for prevalence study

If you find the expected rate or prevalence of the most important question in a survey or field survey from the literature, you can estimate the minimum number of participants required with the help of this menu. If the prevalence is entered as 50%, the largest sample size is calculated.

Required information

Confidence interval: Select between 95% and 99%.

Precision: Enter the value of error you can make when estimating prevalence.

Prevalence: If it is a survey study, enter the percentage of the expected response for one of your questions, or if it is a prevalence study, enter the value of the expected prevalence.

Population: If there is a limited population size, enter the population value to correct the sample size. Leave blank if not required.

Sample calculation: To calculate the minimum number of patients required to estimate the expectation that the prevalence of COVID positivity will be 20% among patients who applied to the chest diseases outpatient clinic with a complaint of cough within 1 year with a 5% error (15%-25%) and a 95% confidence interval, the information should be entered into the application as follows.