Hypothesis Tests and Confidence Intervals for Proportions

[#1]

Use to estimate via a confidence interval and perform hypothesis tests for a population proportion. 

Confidence Intervals for Population Proportions

1. From an open JMP^® data table, select Analyze > Distribution.
2. Select one or more categorical variables from Select Columns, click Y, Columns (categorical variables have red or green bars).
   Note: If you have summarized data (a column with counts), enter the column into Freq.
3. Click OK.
4. In the resulting window, click on the red triangle for the variable and select Confidence Interval > 0.95.
   JMP will produce 95% confidence intervals for the true population proportion for each level.

Car Poll.jmp (Help > Sample Data Folder)

Hypothesis Tests for Population Proportions

1. From the Distribution output window, click on the red triangle for the variable and select Test Probabilities.
2. Enter the hypothesized proportions under Hypoth Prob, and click Done.
   Here we are testing the following set of hypotheses:

H₀: p_Family = 0.5 vs. H_A: p_Family ≠ 0.5
H₀: p_Sporty = 0.3 vs. H_A: p_Sporty ≠ 0.3

H₀: p_Work = 0.2 vs. H_A: p_Work ≠ 0.2

Notes: The hypothesized probabilities must sum to one. You may choose to specify some values and have JMP rescale according to your choice of rescaling method.  

• JMP will provide the results of two chi-square tests: Likelihood Ratio and Pearson.
• The null hypothesis is that the true proportions are equal to the hypothesized values.
• Small p-values (<0.05) indicate that at least one sample proportion is significantly different from the hypothesized value.
• Since the p-values in this example are large (> 0.05), we cannot reject any of the null hypotheses.

This analysis can also be performed using the Hypothesis Test for One Proportion and Confidence Intervals for One Proportion Calculators under Help > Sample Index > Calculators or Student > Calculators in JMP Student Subscription.

Visit Basic Analysis > Distributions > Additional Examples of the Distribution Platform > Example of Testing Probabilities for Two Levels and Example of Testing Probabilities for More Than Two Levels in JMP Help to learn more.