## Sample Size for Measuring Means

In many surveys and studies, the prime variable of interest may be a mean. A few examples are given below:

1. Mean daily protien intake of adolescent girls in Rwanda

2. Mean systolic blood pressure of IT professionals in Bangalore city

3. Mean haemoglobin level among pregnant women in their third trimester, in Sri Lanka

If you want to measure mean through a survey, the sample size calculation will be according to as given below:

1. Mean daily protien intake of adolescent girls in Rwanda

2. Mean systolic blood pressure of IT professionals in Bangalore city

3. Mean haemoglobin level among pregnant women in their third trimester, in Sri Lanka

If you want to measure mean through a survey, the sample size calculation will be according to as given below:

**Single Mean - Absolute Precision Method**

**Single Mean - Relative Precision Method**

**Single Mean - Power Method**

**Single Mean - Power Calculation**

It is one thing to measure a single mean, and it is another thing to compare two means. It is not really a right or recommended way to use the sample size calculation for single mean and apply it to two groups separately and then compare the results. Hence, for comparing two means, refer to the formulae below:

**Comparing Two Means - Power Method**

**Comparing Two Means - Precision Method**

**Comparing Two Means - Power Calculation**

**Comparing Two Means - Detectable Difference**