Matching and sorting data records in a Combined Control Chart

GainSeeker vertically aligns subgroup averages from different retrieval groups that share the date/time stamp or traceability information you specify.

For example, the following chart lines up data points where the Cavity number, Date/Time stamp, and Lot number are identical. Then the points are sorted in order by Cavity number.

If a data record does not match the displayed traceability values of a data record from a different retrieval group, it is still displayed on the Combined Control Chart, as displayed in the first three points on the following chart:

Defining the traceability fields used to match and order data points

By default, Date/Time is the only field used to match data points from different retrieval groups. However, you can configure SPC to match data points by different combinations of traceability fields by following the steps below:

  1. Right-click on the Combined Control Chart window, or click the Options menu.

  2. Select Display Options from the menu.

  3. On the Chart Limits tab, select the check boxes for the traceability and date/time options to use for matching data from different retrievals.  If you clear all the check boxes in this list, the data records from different retrieval groups will be matched by count (first subgroup retrieved for each retrieval group, second subgroup retrieved for each retrieval group, etc.).

The Combined Control Chart will sort the data in order by the first checked item in the Match retrieval group records based on list.  To change the order of items in the list, click one of the checked items and then click the and buttons to move the selected item up or down in the list.

The settings in this list are also used by Multiple Data Tables. If you change these settings for a Combined Control Chart, the settings are also changed for any Multiple Data Table associated with this chart.

  1. After selecting the fields and the order in which to display them, click OK.

Defining how date/time stamps are matched

When matching the date/time stamps of data records from different retrieval groups, SPC actually matches date/time stamps that are close to each other.

By default, date/time stamps within 10 seconds of each other can be considered identical.  However, you can change this time period for date/time matches by adding the mdt_datespan= setting to your Cms.ini file.  Set this option equal to the number of seconds within which two date/time stamps can be considered identical.

Example: Removing date/time offset from a Combined Control Chart

The retrieval groups in the following Combined Control Chart display several lots of a part that goes through one process (the blue line) and then goes through a second process (the red line). The data points are matched only by date/time stamp

A Multiple Data Table displays the data behind this chart.

However, matching the data by lot number instead of date/time stamp shows a different picture.

A Multiple Data Table displays the data behind this chart.

Related topics

Colors and line types on a Combined Control Chart

Scaling a Combined Control Chart