This procedure can calculate power, sample size and minimum difference for 1 Proportion.
1. Choose ProcessMA > Statistics > Power and Sample Size > 1 Proportion.
2. In Objective, choose what you want to calculate.
· If you want to find sample size(s):
- In Alternate p value(s), enter one or more p values, separated by commas(,).
- In Power value(s), enter one or more power values, separated by commas(,).
· If you want to find Alternative p value(s):
- In Sample size(s), enter one or more sample sizes, separated by commas(,).
- In Power value(s), enter one or more power values, separated by commas(,).
· If you want to find power value(s):
- In Sample size(s), enter one or more sample sizes, separated by commas(,).
- In Alternate p value(s), enter one or more p values, separated by commas(,).
3. In Hypothesised p, enter the hypothesised p value.
4. In Alternate, select the type of test.
5. In Significance level, enter the desired significance level.
6. Click OK.
Sample size(s): Integer.
Alternate p value(s): Numeric; Between 0 to 1.
Power value(s): Numeric; Between 0 to 1; Must be greater than the significance level.
Hypothesised p: Numeric; Between 0 to 1.
You are the logistic manager and you need to find out if the proportion of products damaged during transport changed after using a new packaging. Historically the proportion of goods damaged during transport is 0.1. Determine the number of samples you need to detect a difference of 0.05 at a confidence level of 95% (a = 0.05) for a power of 0.9?
1. Choose ProcessMA > Statistics > Power and Sample Size > 1 Proportion.
2. In Objective, select Find sample size(s).
3. In Alternate p value(s), enter 0.05, 0.15.
4. In Power value(s), enter 0.9.
5. In Hypothesised p, enter 0.1.
6. In Alternate, select Not equals.
7. In Significance level, enter 0.05.
8. Click OK.
Interpretation
To detect a change in proportion of -0.05 and +0.05, you need sample sizes of 301 and 438 respectively.