Use a 1 proportion test to analyze the difference between an observed process proportion (defectives) and a specified value.
When to Use | Purpose |
---|---|
Pre-project | Verify the process is producing output significantly different from expectations (in this case, that usually means a higher-than-expected defect rate), which validates the need for an improvement project. |
Mid-project | Test whether the proportion defective changed significantly when an input is controlled at a new setting or a previously uncontrolled setting is now controlled. |
Mid-project | Verify changes from the pre-project standard, throughout the course of making improvements. |
End of project | Verify the proportion defective from the controlled improved process is different from the pre-project proportion defective. Of course, this step assumes one of the goals of the project was to reduce the proportion defective. |
Your data must be discrete Y at exactly two levels (also called binary or binomial data). You can enter the raw data into a single column in Minitab where each row represents one observation. Or, you can enter summarized data (the number of items sampled and the number of defectives observed) in the 1 Proportion dialog box.
For more information, go to Insert an analysis capture tool.
Use a 1-sample t-test to analyze the difference between an observed process mean and a specified value.
When to Use | Purpose |
---|---|
Pre-project | Verify the process is producing output significantly different from expectations, which validates the need for an improvement project. |
Mid-project | Test whether the output changes significantly when an input is controlled at a new setting or a previously uncontrolled setting is now controlled. |
Mid-project | Verify changes from the pre-project standard throughout the course of making improvements. |
End of project | Verify the mean output from the controlled improved process is different from the pre-project mean. Of course, this step assumes that one of the goals of the project was to shift the process mean. |
Your data must be continuous Y (output) values.
For more information, go to Insert an analysis capture tool.
Use a 1-sample Wilcoxon test to analyze the observed difference between a process median and a known value. This test is similar to the 1-sample t-test, and is used as an alternative test for cases in which the data are not reasonably normal.
When to Use | Purpose |
---|---|
Pre-project | Verify that the process is producing output significantly different from expectations, which validates the need for an improvement project. |
Mid-project | Test whether the output changes significantly when an input is controlled at a new setting or a previously uncontrolled setting is now controlled. |
Mid-project | Verify changes from the pre-project standard, throughout the course of making improvements. |
End of project | Verify that the median output from the controlled improved process is different from the pre-project median. This step assumes one of the goals of the project was to shift the process median. |
Your data must be a continuous value for Y (output).
For more information, go to Insert an analysis capture tool.
Use a 1 variance test to analyze the difference between an observed process standard deviation (or variance) and a specified value.
When to Use | Purpose |
---|---|
Pre-project | Verify the variability of the process is significantly different from expectations, validating the need for an improvement project. |
Mid-project | Test whether a significant change has occurred in the variability of the output when an input is controlled at a new setting or a previously uncontrolled setting is now controlled. |
Mid-project | Verify changes from the pre-project standard, throughout the course of making improvements. |
End of project | Verify the variability of the controlled improved process is different from the pre-project variability. Of course, this assumes that one of the goals of the project was to reduce the variability of the process. |
Your data must be continuous Y (output) values.
For more information, go to Insert an analysis capture tool.
Use a 1-sample sign test to analyze the observed difference between a process median and a known value. This test is similar to a 1-sample t-test, and is used as an alternative for cases where the data are not reasonably normal.
When to Use | Purpose |
---|---|
Pre-project | Verify the process is producing output significantly different from expectations, validating the need for an improvement project. |
Mid-project | Test whether the output changes significantly when an input is controlled at a new setting or a previously uncontrolled setting is now controlled. |
Mid-project | Verify changes from the pre-project standard throughout the course of making improvements. |
End of project | Verify the median output from the controlled improved process is different from the pre-project median. Of course, this step assumes that one of the goals of the project was to shift the process median. |
Your data must be a continuous value for Y (output).
For more information, go to Insert an analysis capture tool.