Test of a Proportion

Jay Arthur
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Use our proportion test template to compute a confidence interval and perform a hypothesis test of the proportion.

For example, if a manufacturer claims that his products are less than 3% defective, you can take a sample of products and determine whether or not the actual percent defective is consistent with his claim.

Here is how to perform a Test of Proportion using the QI Macros Proportion template:

1. If data isn't summarized, use PivotTables to summarize the trials and successes
2. Click on the QI Macros pull down menu and select Anova and Analysis Tools, then Proportion tests.



3. Enter test proportion in A3 (e.g., 3% is 0.03).
4. Enter number of trials in B3 (100 products)
5. Enter number of successes in C3 (e.g., defects in 100 products)
6. Enter confidence Level in E1 (.95 = 95%)
7. Null hypothesis is H1=H0 (sample proportion = proportion). p values are calculated via direct and normal approximation methods for H1<>H0, H1>H0 and H1<H0.
   • If Cell H3:H5 (or J3:J5) is green, you cannot reject the null hypothesis
   • If Cell H3:H5 is red, reject the null hypothesis

In this example with five defects in 100 samples, you cannot reject the null hypothesis.

Other Statistical tests in the QI Macros

• Anova
• Data normality test
• t test in Excel
• Test of Two Proportions

The Test of Proportion template is just one of the tools included in the QI Macros for Excel SPC Software for Excel.

Download the FREE 30-day Evaluation copy of the QI Macros Excel SPC Software for Six Sigma