Exclude Data Points

The Joinpoint software was updated to allow users to exclude multiple data points from their data prior to fitting the models.  This capability may be useful in situations such as analyses impacted by the COVID-19 pandemic. 

Users can exclude select data points from the modeling by using the “Define…” dialog in the Independent Variable section of the Joinpoint session.  By using the checkboxes in the Include Observation in Modeling column in the dialog, users can exclude data points.  The following restrictions have been implemented:

• The option can only be used when users provide their pre-calculated observed values (rates, counts, percentages, etc.). Any option where Joinpoint computes the observed values (computed age-adjusted rates, proportions, etc.) is not supported currently.
• There must be at least two data points included.
• If the Advanced Analyses option of “Jump Model/Comparability Ratio Model” is used, the last observation of old coding and the first observation of new coding MUST be included.

The results for each model will be based on all the data points except the excluded point(s).  After fitting the models to the data, the excluded data point(s) will be inserted back in for graphing purposes.  The excluded data point(s) will also be displayed on the data tab in the output.

When viewing the graph, the last line segment will go up to the last included data point.  Each excluded observed data point will be shown in the graph, but with a different color.  Also, on the data tab there will be a modeled value for each excluded data point. The modeled value was calculated from the results of the model fit (which excluded the data point) and is provided for graphing purposes outside of Joinpoint.

AAPC Ranges

When excluding data points, the last “N” AAPC range may be affected.  Below are some scenarios that can occur when excluding data points. Each is accompanied by an example when you have specified the last 5 AAPC range and have data through 2022:

• If a data point within the AAPC range other than the last point(s) is excluded, then the last “N” AAPC range will count the excluded data point.
• For the last 5 AAPC range, if 2018, 2019, 2020, or 2021 is excluded (or any combination of them), the range will be 2018-2022.
• If the last data point or data points are excluded, the last “N” AAPC range will not include those points.
• For the last 5 AAPC range, if 2022 is excluded, the range will be 2017-2021.
• For the last 5 AAPC range, if 2021 and 2022 are excluded, the range will be 2016-2020.

If you set an AAPC range that includes the ends of the data range and then exclude the observations at the ends of the data, the AAPC ranges will be updated to reflect the new ends of the data.

The full AAPC range will run from the first included data point through the last included data point.