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Data Files Containing Cohorts with an Unequal Number of Observations

- Joinpoint can process data files that contain cohorts with an unequal number of observations.

Reading the Input File and Populating the Independent Variable:

When all of the input variables on the Input File tab of the session have been specified, Joinpoint will read the data file.  The Independent variable format will be populated with all the unique variable values found in the data file and the Maximum Number of Joinpoints (on the Method and Parameters tab) will be assigned based on the cohort with the maximum number of observations.   When a user executes their session Joinpoint will check to make sure every cohort has enough observations to be run with the selected Maximum Number of Joinpoints.

What happens when the maximum number of Joinpoints is enough for all cohorts?

If you have specified a Maximum Number of Joinpoints that is low enough to satisfy the default maximum requirement for all cohorts, Joinpoint will execute as normal.  However, if the data file contains cohorts that have fewer observations than recommended for the specified Maximum Number of Joinpoints, Joinpoint will display a dialog asking you to choose how to handle those cohorts.

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  1. Use the recommended default maximum number of Joinpoints for all cohorts. This option will use the recommended number of Joinpoints based on the number of observations in each cohort as defined here.
  2. Lower the maximum number of joinpoints to the number closest to the Maximum Number of Joinpoints specified in the session. The recommended default maximum number of Joinpoints are based solely off of the number of observations, but other settings are involved when determining what the maximum number of Joinpoints a cohort can actually be run with (click here to learn more about these settings.)  This option will lower the maximum number of Joinpoints by 1 until Joinpoint finds the maximum closest to what was set in the session that it can use to execute the cohort.  For example, a cohort with 8 observations would set the Maximum Number of Joinpoints to 1 by default.  However, under the other default settings, Joinpoint could execute this cohort with the Maximum Number of Joinpoints set to 2.  If a file had some cohorts with 18 observations and some with 8 observations, the Maximum Number of Joinpoints would be set to 3 by default.  This option will execute the cohorts with 8 observations with a Maximum Number of Joinpoints set to 2.
  3. Do not execute cohorts that do not have enough observations to meet the default recommendations. When using this option, Joinpoint will still display a plot of the observed data on the graph tab and the observations on the data tab, but no other statistics will be produced.  Cohorts that are not executed will be flagged with the following:
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