Example of Sample Size for Estimation

An analyst at an electronics company uses a sample size for estimation calculation before conducting a study to estimate the mean voltage of a new line of resistors used in circuit boards. The analyst wants to know what sample size is required to obtain a margin of error of 5. Based on previous studies, the standard deviation is 22.5.

  1. Choose Stat > Power and Sample Size > Sample Size for Estimation.
  2. In Parameter, select Mean (Normal).
  3. Under Planning Value, enter 22.5 in Standard deviation.
  4. In Margins of error for confidence intervals, enter 5.
  5. Click OK.

Interpret the results

To achieve a margin of error of 5 when estimating the mean voltage of resistors, the analyst needs to collect a sample size of 81.

Sample Size for Estimation

Method

Parameter Mean Distribution Normal Standard deviation 22.5 (estimate) Confidence level 95% Confidence interval Two-sided
Results Margin Sample of Error Size 5 81
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