Crunch offers controls for warning or suppressing values calculated from unweighted bases that fall below a customizable threshold. This is a dataset-level property and can be set by any dataset editor.
See General Properties to learn more about how to turn this feature on and how to set the threshold.
Warning vs Suppression
Although both warning and suppression behavior use the same threshold, they operate differently when applied to analyses.
Warning behavior
Warnings are only applied to tables and do not impact graphs. When a value in a table is calculated from an unweighted base below the threshold, it will be displayed in light gray and a footer will be shown reminding users that “Values in light gray are based on valid Ns of fewer than [x]” where x is the minimum base size threshold set for the current dataset. This applies to the cards in Variables Summaries mode, tables in Tables & Graphs mode, and tables in Multitables mode. It also applies to table exports from the deck and tab-books.
Suppression behavior
Unlike warnings, suppression is applied to both tables and graphs. In Tables & Graphs mode and in Multitables mode, table cell values calculated from an unweighted base below the threshold will be replaced with a long-dash symbol and a footnote will be shown reminding users that there are “Columns [/Rows] that have categories with fewer than [x] cases” where x is the minimum base size threshold set for the current dataset. Suppression is not applied to the cards of Variable Summaries mode.
Suppression behavior for different visualization types
Vertical or horizontal bar
Low base size categories are not plotted, as if those categories didn't exist. Their bases are subtracted from the total N value shown on the plot.
Vertical or horizontal grouped bar
The base size thresholds are applied to the percentages (column, row, or total), and these are the axis categories. Axis categories with low base sizes are not plotted, which therefore applies to all of the bars in that group. Their bases are subtracted from the total N value shown on the plot.
Vertical or horizontal stacked bar
The base size thresholds are applied to the percentages (column, row, or total), and these are the axis categories. Axis categories with low base sizes are not plotted, which therefore applies to all of the segments in that stack. Their bases are subtracted from the total N value shown on the plot.
Donut
Donut charts are only offered for single-dimension categorical analyses, and they only have one base value. The whole visualization is therefore either above or below the threshold. If it's below, the whole donut chart is not displayed.
Line
The base size thresholds are applied to the percentages (column, row, or total), and these are the x-axis time period categories. X-axis categories with low base sizes are not plotted as if those waves didn't ask that question, though the wave still exists and the previous and next points will therefore be joined by a dotted line to indicate that a wave was skipped. Their bases are subtracted from the total N value shown on the plot. The draggable 'inspector bar' won't stop at those points.
Dot
Means based on a low valid base are not plotted.
Histogram
For single-dimension numeric variables which therefore only have one base value, the whole visualization is either above or below the threshold. If it's below, the whole histogram is not displayed. For the case where a numeric variable has been crossed by another variable, resulting in multiple histograms, the base size thresholds are applied to the percentages (column, row, or total), and these are each of the stacked histograms. Histograms with low base sizes are not plotted, though their bases still count towards the total N value shown on the plot.
KPI widget
A KPI is a single cell from a table. As such, the value in that table cell may be replaced by a dash depending on all the criteria already discussed. Under these circumstances, the KPI widget shows a long dash instead of the value.
Whole graph suppression
Where a whole visualization can no longer be shown due to a low base size, we show a message in place of the graph that reads "Insufficient data" followed by "Below <n>" where n is the min base size.
