Sample Size Calculation, Two Proportions, Z-Test

Sample Size calculation for two independent proportions via Z-Test with option for charts of sample size vs. population one proportion value, 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).
Pi1 Population number one proportion (acceptable range 0.0001 < Pi1 < 0.999).
Pi2 Population number two proportion (acceptable range 0.0001 < Pi2 < 0.999).
Sample One Size Sample size of group one for the sample size calculation (acceptable range 2 to 150000).
Sample Two Size Sample size of group two for the sample size calculation (acceptable range 2 to 150000).
Alpha Level Alpha level (Type I error rate for Z-statistic) (acceptable range 0.0001 to 0.25).
Hypothesis type Hypothesis type selection:

 Two-tailed (Pi1<=Pi2, population one proportion = population two proportion);

 One-tailed (Pi1<=Pi2, population one proportion <= population two proportion);

 One-tailed (Pi1>=Pi2, population one proportion >= population two proportion).
Applies Continuity Correction Type of calculation selection:

 If TRUE, apply the continuity correction.
Employ Equal Ns Type of calculation selection:

 If TRUE, limit group 1 and group 2 to the same sample size (Sample size specified for Sample One Size will apply to both N1 and N2);

 If FALSE, N1 and N2 can be varied independently for the analysis.
N to Vary Find sample size for one or both groups:

 Equal N (vary N1 and N2 simultaneously and equally);

 Vary N1 (Vary N1 while holding N2 constant at the value specified under Sample Two Size above);

 Vary N2 (Vary N2 while holding N1 constant at the value specified under Sample One Size above).

 Fixed Ratio (Vary N1 and N2 in a fixed ratio to be specified in the parameter following).

 This option also applies to any charts that are produced.

General, cont

Element Name Description
Fixed Ratio Value When the Fixed Ratio option for the N to Vary parameter is selected, this ratio will be applied in the sample size calculation (acceptable range 0.01 to 100.0).
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. Population One Proportion, 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 Proportion (Pi1). (For charts only) Initial population one proportion value for calculation of Sample Size vs. Population One Proportion chart (acceptable range 0.0001 to 0.9999).
Ending Proportion (Pi1). (For charts only) Final population one proportion value for calculation of Sample Size vs. Population One Proportion chart (acceptable range 0.0002 to 1.0).
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).