- Display one
probability plot per graph
- Select to display one probability plot per graph. By default, Minitab displays four probability plots per graph.
- Do not display
confidence intervals on probability plots
- Select to display probability plots without confidence intervals.
- Enter a confidence level between 0 and 100. Usually, a confidence level of 95% works well. A 95% confidence level indicates that if you took 100 random samples from the process, you could expect approximately 95 of the samples to produce confidence intervals that contain the actual value of the percentile for the process (if all the process data could be collected and analyzed).
- For a given set of data, a lower confidence level produces a narrower confidence interval, and a higher confidence level produces a wider confidence interval. The width of the interval also tends to decrease with larger sample sizes. Therefore, you may want to use a confidence level other than 95%, depending on your sample size, as follows:
- If your sample size is small, a 95% confidence interval may be too wide to be useful. Using a lower confidence level, such as 90%, will produce a narrower interval. However, the likelihood that the interval contains the actual percentile value for the process decreases.
- If your sample size is large, you may want to consider using a higher confidence level, such as 99%. With a large sample, a 99% confidence level may still produce a reasonably narrow interval while increasing the likelihood that the interval contains the actual percentile value for the process.
You can specify default settings for the Y-scale type, the graph orientation, and the method for calculating the plot points using