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Design of Experiments Guide > Sample Size Explorers > Confidence Interval Explorers > Margin of Error for Two Independent Counts per Unit
Publication date: 04/21/2023

Margin of Error for Two Independent Counts per Unit

Use the Margin of Error for Two Independent Counts per Unit to determine a sample size for a confidence interval. Select DOE > Sample Size Explorers > Confidence Intervals > Margin of Error for Two Independent Counts per Unit. Explore the trade offs between sample size, significance, and the margin of error for your interval.

Interval Explorer for Differences in Group Counts per Unit 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 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 Differences in Group Counts per Unit Profiler

The profiler enables you to visualize the impact of sample size assumptions on the margin of error calculations.

Total Sample Size

Specifies the total number of observations (runs, experimental units, or samples) needed for your experiment. The margin of error curve is based on total sample size. Select Lock to lock the total sample size.

Solve for

Enables you to solve for a sample size or an assumed proportion.

Total Sample Size

Specifies the total number of observations (runs, experimental units, or samples) needed for your experiment.

Group 1 Sample Size

Specifies the number of observations (runs, experimental units, or samples) needed for Group 1 in your experiment.

Group 2 Sample Size

Specifies the number of observations (runs, experimental units, or samples) needed for Group 2 in your experiment.

Group 1 Counts per Unit

Specifies the assumed counts per unit for Group 1.

Group 2 Counts per Unit

Specifies the assumed counts per unit for Group 2.

Note: Adjusting the sample size for one group adjusts the total sample size unless the total sample size is locked. In that case, adjusting the sample size for one group adjust the sample size for the second group.

Interval Explorer for Differences in Group Counts per Unit 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 Differences in Group Counts per Unit

The calculations for each interval type are based on the asymptotic normal distribution.

The margin of error (MOE) is calculated as follows:

Equation shown here

The bounds are calculated as follows:

Equation shown here

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.

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