Sample Size Calculation, Two Means, t-Test, Independent Samples

Sample Size calculation for two independent samples t-tests with options for charts of sample size vs. standardized effect, sample size vs. alpha level, and sample size vs. power.

General

Element Name Description
Power Goal Specifies Power Goal for the Sample Size calculation (acceptable range 0.65 to 0.9999).
Mu1 Population number one mean.
Mu2 Population number two mean.
Population Standard Deviation Standard deviation of the population.
Alpha Level Alpha level (Type I error rate for t-statistic) (acceptable range 0.0001 to 0.25).
Hypothesis type Hypothesis type selection:

 Two-tailed (Mu1=Mu2, population one mean=population two mean);

 One-tailed (Mu1<=Mu2, population one mean <= population two mean);

 One-tailed (Mu1>=Mu2, population one mean >= population two mean).
Detail of computed results reported Output level of detail selection:

 Sample Size Calculation produces Sample size Calculation Spreadsheet;

 Smpl Size Calc plus Charts option produces, in addition, Sample Size vs. Standardized Effect, Sample Size vs. Alpha Level, and Sample Size vs. Power charts.

Chart Parameters

Element Name Description
Number of Steps. (For charts only) Number of individual steps for which to calculate Sample Size between the starting and ending parameter values for Sample Size Charts (Min 4, Max 100).
Starting Power. (For charts only) Initial power value for calculation of Sample Size vs. Power charts (acceptable range 0.05 to 0.99).
Ending Power. (For charts only) Final Power value for calculation of Sample Size vs. Power charts (acceptable range 0.1 to 0.999).
Starting Standardized Effect. (For charts only) Initial standardized effect size value for calculation of Sample Size vs. Standardized Effect chart (acceptable range -10 to 9).
Ending Standardized Effect. (For charts only) Final standardized effect size value for calculation of Sample Size vs. Standardized Effect chart (acceptable range -9 to 10).
Starting Alpha. (For charts only) Initial alpha value for calculation of Sample Size vs. Alpha Level chart (acceptable range 0.0001 to 0.2499).
Ending Alpha. (For charts only) Final alpha value for calculation of Sample Size vs. Alpha Level chart (acceptable range 0.0002 to 0.25).