Comparing 2 Proportions: Power Calculation Results - Quick Tab
Calculating Power
Select the Quick tab of the Comparing 2 Proportions: Power Calculation Results dialog box to access options to interactively view the results of power calculations and generate plots of power as a function of quantities that affect power 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 Power Charts.
- Start N
- In the Start N box, enter the starting value of N used in the Power vs. N power chart.
- End N
- In the End N box, enter the final value of N used in the Power vs. N power chart.
- Start Pi1
- In the Start Pi1 box, the starting value of Pi1 used in the Power vs. Pi1 power chart.
- End Pi1
- In the End Pi1 box, enter the final value of Pi1 used in the Power vs. Pi1 power chart.
- Start Alpha
- In the Start Alpha box, enter the starting value of alpha used in the Power vs. Alpha power chart.
- End Alpha
- In the End Alpha box, enter the final value of alpha used in the Power vs. Alpha power chart.
- No. of Steps.
- In the No. of Steps box, enter the number of steps, or intervals, to plot on the X-axis in the power charts specified in the Power Charts group box.
- Power Charts
- Use the buttons under Power Charts to produce charts of power as a function of values known to affect it. Note that parameters given in the X-Axis Graphing Parameters group box control the range of values plotted on the X-axis and the number of steps plotted.
- Power vs. N.
- Click the Power vs. N button to produce a plot of power versus sample size N, for a two sample Z-statistic where both sample sizes are equal to N.
- Power vs. N1.
- Click the Power vs. N1 button to produce a plot of power versus group 1 sample size, where the group 2 sample size is held constant at the current fixed parameter value.
- Power vs. N2.
- Click the Power vs. N2 button to produce a plot of power versus group 2 sample size, where the group 1 sample size is held constant at the current fixed parameter value.
- Power vs. Pi1.
- Click the Power vs. Pi1 button to produce a plot of power vs. the population proportion for group 1.
- Power vs. Alpha.
- Click the Power vs. Alpha button to produce a plot of power versus type I error rate.
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