Contents
- Index
Data Window
The Data window is a permanent child window for entering the data to be analyzed. Each set of data should be entered on a separate tab sheet. The columns for entering the data are:
Data Values Column: Enter the values to be analyzed. Generally a minimum of 15 values must be entered but this can be changed to as few as 8 using the Advanced Options dialog box.
Order Column: Optionally, enter the time order the values were collected in. This may be either numbers or labels. The data does not have to appear in time order as the values entered in the Order column are sorted into numeric or alphanumeric order. If several values are taken at the same time, use the same number or label for all values. The order column can be automatically filled by clicking the Fill Order/Group Column button to display the Fill Order/Group Column dialog box. If the order is specified, additional analysis is performed to see if the values shifted over time and the results are displayed in the Order - Analysis tab of the Test Distribution window.
Group Column: Optionally, enter the group (cavity, operator, line, lot, etc.) associated with each value. This may be either numbers or labels. The group column can be automatically filled by clicking the Fill Order/Group Column button to display the Fill Order/Group Column dialog box. If the groups are specified, additional analysis is performed to see if the groups are different and the results are displayed in the Group - Analysis tab of the Test Distribution window.
Transformed Values Column: You cannot type into this column. Instead it is used to display the transformed values. If no distribution/transformation is selected, the values are identical to the first column. Distributions/transformations are selected by clicking the Find Best Distribution or Select Distribution buttons.
Either type the data in directly or paste it from the clipboard using the Paste menu item. The Edit menu has further menu items for selecting, copying, cutting and clearing cells as well as for adding, moving, deleting and renaming tab sheets. A short cut for renaming a sheet is to double click on the tab of the sheet. Use the Tab, Shift+Tab, Enter, Page Up, Page Down, Home, End and arrow keys to move around the cells. Use the Shift+Arrow keys to increase or decrease the size of a selected region. Click on the Print button to print a copy of the data.
In addition, each tab sheet contains the following controls for entering additional information:
Characteristic Edit Box: Optionally, use to enter the name of the characteristics. If no characteristic is entered, the name of the sheet is used.
Units Edit Box: Optionally, use to enter the units for the characteristic.
I.D. Edit Box: Optionally, use to further differentiate data sets with product name, lot number, lane, cavity etc.
Date Edit Box: Optionally, used to enter date or any other further information.
Lower Spec Limit Edit Box: Used to enter the lower spec limit, if one exists.
Upper Spec Limit Edit Box: Used to enter the upper spec limit, if one exists.
Lower Bound Edit Box: Used to enter the lower bound, if one exists. This bound can be used to pre-transform the data.
Upper Bound Edit Box: Used to enter the upper bound, if one exists. This bound can be used to pre-transform the data.
Once the data is entered, it is time to perform the analysis. Use the following buttons:
Test Distribution Button: Displays the Test Distribution window where the data is analyzed to see if the selected distribution fits the data. The selected distribution is displayed in the Selected Distribution group box. It is initially set to "No Transformation (Normal Distribution)", in which case the data is tested to see if it fits the normal distribution. Additional analysis are also performed including: estimates of moments, capability indexes, tolerance interval, confidence statement relative to spec limits, test if order effect, test if groups are different and check for outliers.
Find Best Distribution Button. Used to determine which of the available distributions best fits the data with or without pre-transforming the data. The result is displayed in the Selected Distribution group box. The distribution producing the highest p-value for the Skewness-Kurtosis All Test for normality when applied to the transformed data is selected, excluding those not including the spec limits within the range of the distribution.
Select Distribution Button. Displays popup menu shown below for selecting a specific distribution. If your data commonly fits a distribution other than the normal distribution, then select it using this menu. When a distribution is selected, it is fit to the data using both method of moments and maximum likelihood. The best fit is returned. If you don't know what distribution to use, click the Find Best Distribution button instead. The following distributions and family of distributions can be fit: Beta, Exponential, Negative Exponential, Largest Extreme Value, Smallest Extreme Value, Gamma, Johnson, Loglogistic, Lognormal, Normal, Pearson and Uniform. The Custom menu item displays the Select Distribution to Fit Data dialog box. This dialog gives you complete control over the process including the distribution to fit, the method used to fit the data and whether to pre-transform the data or not. The difference between selecting the No Transformation menu item and the Normal menu item is that the No Transformation menu item does not transform the data (Y=X) and the Normal menu item transforms the data using the transformation Y = (X-Average) / Standard Deviation.
Skewness-Kurtosis Plot Button. Displays the Skewness-Kurtosis Plot window for exploring the shapes and relationships of the different distributions. The skewness and kurtosis of any entered data is also displayed on the plot as an aid in identifying which distributions might fit the data.
There are menu items on the Analysis menu and buttons on the toolbar that correspond to the Test Distribution, Find Best Distribution, Skewness/Kurtosis Plot, Select Distribution and Fill Order/Group Column buttons.