Margin of Error for One Sample Proportion
Use the Margin of Error for One Sample Proportion to determine a sample size for a confidence interval. Select DOE > Sample Size Explorers > Confidence Intervals > Margin of Error for One Sample Proportion. Explore the trade offs between the assumed proportion, sample size, significance, and the margin of error for your interval. Calculations use score confidence intervals.
Interval Explorer for One Sample Proportion Settings
Set study assumptions and explore sample sizes using the radio buttons, text boxes, and menus. The profiler updates as you make changes to the settings. Alternatively, change settings by dragging the cross hairs on the profiler curves.
Interval Type
One-sided
Specifies a one-side of the interval (upper or lower bound)
Two-sided
Specifies a two-sided interval.
Preliminary Information
Alpha
Specifies the confidence level, 1 - Alpha. The default alpha level is 0.05 for a 95% confidence interval.
Interval Explorer for One Sample Proportion Profiler
The profiler enables you to visualize the impact of sample size assumptions on the margin of error calculations.
Solve for
Enables you to solve for the sample size or assumed proportion.
Margin of Error
Specifies the half-width of the interval. With all other parameters fixed, margin of error decreases as sample size increases.
Sample Size
Specifies the total number of observations (runs, experimental units, or samples) needed to construct your interval.
Proportion
Specifies the assumed proportion for the interval.
Interval Explorer for One Sample Proportion Options
The Explorer red triangle menu and report buttons provide additional options:
Simulate Data
Opens a data table of simulated data based on the explorer settings. View the simulated response column formula for the settings used.
Make Data Collection Table
Creates a new data table that you can use for data collection. The table includes scripts to facilitate data analysis.
Save Settings
Saves the current settings to the Saved Settings table. This enables you to save a set of alternative study plans. See Saved Settings in the Sample Size Explorers.
Help
Opens JMP help.
Statistical Details for the One Sample Proportion Interval Explorer
The interval calculations for capturing a population proportion is based on the Agresti-Coull method, see Agresti and Coull(1998). This method is also known as score confidence intervals.
The margin of error (MOE) for confidence intervals is calculated as follows:
The bound is calculated as follows:
where
and
and q = 1 - α/2 for an interval or q = 1 - α for a bound.