Digit Preference

This report assesses the use of terminal digits (either first or last in numerical findings) by study sites when reporting their clinical findings. It can be used to identify those sites that might exhibit biases in rounding issues or other problems with how they report data as compared with all other sites in the study.

Report Results Description

Running Digit Preference for Nicardipine using default settings generates the report shown below.

Digit Preference Volcano Plot

• In this volcano plot each point represents the comparison of a site to all other sites. This comparison is used to determine whether there is a difference in distribution for the last digit for a findings test with numeric data available and is done for all sites across all tests in all findings domains.

The Y axis is the -log10(Raw Row Mean Score p-value), which takes advantage of the ordinality of the final digit value, This test uses standardized midrank scores in case there are gaps due to certain digit values not present. Midranks are a way of scoring the columns when the distance between levels does not necessarily have a practical interpretation. Large numbers on the Y axis indicate statistically significant results.

The X axis is the maximum percent difference1 across all digits between a site versus all sites. Values far from 0 indicate important differences between a site and the reference distribution of all other sites. This could identify rounding issues or other problems with how a site reports a particular test compared to other sites.

Options

Data

Summarize sites with at least this many subjects:

The Summarize sites with at least this many subjects: widget enables you to set a minimal threshold for the sites to be analyzed. Only those sites which exceed the specified number of subjects are included. This feature is useful because it enables you to exclude smaller sites, where small differences due to random events are more likely to appear more significant than they truly are. In larger sites, observed differences from expected attendance due to random events are more likely to be significant because any deviations due to random events are less likely to be observed.

Remove unscheduled visits

You might or might not want to include unscheduled visits when you are analyzing findings by visit. Check the Remove unscheduled visits to exclude unscheduled visits.

Display

Report Subject Filters

These filters enable you to subset and view subjects based on on study site, test, and digit. Refer to Data Filter for more information.

General and Drill Down Buttons

Action buttons, provide you with an easy way to drill down into your data. The following action buttons are generated by this report:

• Click to rerun the report using default settings.
• Click to view the associated data tables. Refer to Show Tables/View Data for more information.
• Click to generate a standardized pdf- or rtf-formatted report containing the plots and charts of selected sections.
• Click to generate a JMP Live report. Refer to Create Live Report for more information.
• Click to take notes, and store them in a central location. Refer to Add Notes for more information.
• Click to read user-generated notes. Refer to View Notes for more information.

Default Settings

Refer to Set Study Preferences for default Subject Level settings.

Methodology

Compare the observed distribution of the last or first digit for each test with each site (the suspect site, indexed with s) compared to all other sites taken together as a reference (indexed as o).

 

 

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Compared using a row mean score chi-square tests (Stokes et al., 2012)2 to take advantage of the ordinality of the column variable.

Scores are based on standardized midranks , often used when column values cannot necessarily be considered equally spaced (which tends to happen if not all digits are presented).

FDR p-values are calculated and the reference line is determined as described in How does JMP Clinical calculate the False Discovery Rate (FDR)?.

The Subset of Visits to Analyze options enables you to restrict to a specific subset of visits your search tests with similar and questionable results.