How to Apply Significance Testing in Displayr

Introduction

This article describes how to go from a standard table in Displayr showing no significant differences: 

To a table that shows cell comparison significant differences:

Requirements

• A document containing a table that is cross-tabbed by a variable so that each column represents a different category. 

Method

To perform significance testing in Displayr:

• In the Object Inspector, select Properties > Appearance > Significance
  
  
  

You can select Arrows and Font Colors, or you can select Arrows OR Font colors individually if you instead prefer to show one or the other. These will conduct exception tests, also called complement tests, where the value in a cell is tested against the value of respondents not in that column, or its exception. You can also select Compare columns to perform column comparisons, also called pairwise testing. 

Select the Advanced option if you want complete control over significance testing. 

Using the Advanced option: 

1. Select the table you want to perform significance testing on. 
2. From the Object Inspector, select Properties > Appearance > Significance> Advanced.
   
   You will see the Advanced Statistical Testing Assumptions dialog:
   
3. Select from one of the four tabs on the top depending on the type of task you want to perform:
   • Significance Levels: 
     • Show significance: show higher or lower significance with arrows, font colors (tables only), or using symbols to show significant differences between columns
     • Overall significance level: is used when determining which results to show as being statistically significant
     • Minimal sample size for testing: where cells have sample sizes of less no significance test is conducted when conducting automated tests of statistical significance between cells (i.e., Cell Comparisons and Column Comparisons).
     • Extra deff: by default, the deff value (design effect) is set to 1.00
     • Significance levels and appearance:  symbols used to denote different levels of statistical significance.
   • Test Type: 
     • Proportions: non-parametric tests will be done on categorical data
     • Means: t-test will be done on numeric data and corrected with Bessel’s correction
     • Correlations: default is Pearson
     • Equal variance in tests when sample size is less than: if the sample size is less than 10 variance is assumed equal.
   • Exceptions Test: 
     • Multiple comparison correction: False Discovery Rate is by default applied to help reduce the number of false positives based on the entire table. A check box is available if instead, you prefer to apply the correction within each span within each row.
   • Column Comparisons:
     • Multiple Comparison correction: the following corrections are available for post hoc testing: Fisher LSD, Duncan, Newman Keuls (S-N-K), Tukey HSD, False Discovery Rate (FDR), False Discovery Rate (pooled t-test), Bonferroni, Bonferroni (pooled t-test), Dunnett.
     • Overlaps: The default is to ignore the sample that overlaps between columns when respondents in columns are not mutually exclusive
     • No test symbol: - is shown if a test isn’t performed due to settings
     • Symbol for non-significant test: nothing is shown if a test comes back insignificant
     • ANOVA-Type Test: Select whether ANOVA-type tests are run as part of the testing
     • Show redundant tests: Select whether to show significance on one cell (the one with the higher value) or all cells involved in testing.
     • Show as groups: Show letters for insignificant columns rather than significant
     • Recycle column letters: Each span begins labeling columns at A

Restore to Document settings

To revert to document settings:

• Click the Restore button 

Note: The Restore button will only be enabled when settings for the selected item(s) are different from the document settings (settings saved by Apply as Default). The Restore button will be disabled if you did not save any settings for the selected item(s).

See Also

How to Set the Default Significance Testing 

How to Compare Significant Differences Between Columns

How to Conduct Significance Tests by Comparing to Previous Time Periods

How to Change the Confidence Level at which Significant Differences are Displayed

How to Apply Multiple Comparison Correction to Exception Tests