This calculator is used to test a single proportion to a norm. One of the most common tests, it can be used to determine if one product is preferred significantly over another in a two product use test.

Step 1

Select desired confidence level:

90 95 99  %

Step 2

Enter norm:
Enter a number between 1 and 100. If unsure, use the default value of 50.

 %

Step 3

Enter number of respondents selecting the first alternative:
Enter a positive number for frequency.

frequency

%
percent

Step 4

Enter number of respondents selecting the second alternative:
Enter a positive number for frequency.

frequency

%
percent

RESULTS

2-Tail

%

 %

What the results mean

When you ask respondents which of two products or services they prefer, a researcher would like to know if one product is preferred significantly over the other product. There is some likelihood (confidence level) that the study results will show one of the two products to be preferred significantly over the other. If the Z-value obtained from this test is greater than the value from the Binomial Tables for a given confidence level, the product would be significantly preferred over the other product.

More information

Step 1 – Confidence Level

The value chosen in Step 1 determines the confidence level of your results. It tells you the likelihood that the difference in proportions is NOT due to random chance. For most marketing research studies, a confidence level of 95% is used.

Confidence level is related to the level of significance (α ). A 95% Confidence level corresponds to α = .05. If the Level of significance (α) = .05, that means that there is one chance in twenty that the true population proportion is not statistically significant.

Step 2 – Enter norm

In most instances, researchers will use the value 50% which indicates that the two products are assumed equal (at parity). If a significant value is obtained it is then said that the product’s are not at parity and that one is significantly preferred over the other.

Step 3 – Enter number of respondents selecting first alternative (product)

Enter the number of respondents selecting the first alternative (product). The number should be a positive number and represent the actual frequency of those who chose (preferred) the first product.

Step 4 – Enter number of respondents selecting second alternative (product)

Repeat Step 3 this time entering the number of respondents selecting the second alternative (product). The number should be a positive number and represent the actual frequency of those who chose (preferred) the first product.

Click the calculator button to obtain the results of the test.

Assumptions

This test assumes that your sample size is 30 or larger.

The calculator on this page includes the continuity correction which compensates for the discontinuity of the discrete binomial distribution. This correction is recommended when sample sizes are only modestly large but it is acceptable to use this correction for all sample sizes.

This calculator calculates both one-tail and two-tailed tests. If you are testing the null hypothesis that the two alternatives are equal, use the two-tailed test result.