Calculating Required Sample Size

Select the Quick
tab of the One
Variance: Sample Size Calculation Results dialog box to access options
to interactively view the results of sample size calculations and generate
plots of required sample size as a function of quantities that affect
sample size in practice.

X-Axis Graphing Parameters. The entries in the boxes under X-Axis Graphing Parameters establish the start value, end value, and number of steps on the X-axis for the graphs specified under Sample Size Charts.

Start Power. In the Start
Power box, enter the starting value of power goal used in the Df
vs. Power

End Power. In the End
Power box, enter the final value of power goal used in the Df vs.
Power

Start Var. In the Start Var box, enter the starting value of Var used in the Df vs. Var sample size chart.

End Var. In the End Var box, enter the final value of Var used in the Df vs. Var sample size chart.

Start Alpha. In the Start Alpha box, enter the starting value of a used in the Df vs. Alpha sample size chart.

End Alpha. In the End Alpha box, enter the final value of a used in the Df vs. Alpha sample size chart.

No. of Steps. In the No. of Steps box, enter the number of steps, or intervals, plotted on the X-axis in the power charts specified in the Sample Size Charts box.

Sample Size Charts.
Use the buttons under Sample
Size Charts to produce charts of required N as a function of power
goal, population variance, or type I error rate. The range of values plotted
on the X-axis, and the number of steps plotted, are controlled by parameters
in the X-Axis Graphing Parameters
box.

Df vs. Var. Click the Df vs. Var button to produce a plot of degrees of freedom (Df) versus population variance (Var).

Df vs. Alpha. Click the Df vs. Alpha button to produce a plot of degrees of freedom (Df) vs. Type I error rate.

Df vs. Power. Click the Df vs. Power button to produce a plot of degrees of freedom (Df) versus power goal.