How to Conduct One-Tailed Column Comparisons

By default, Column Comparisons in Displayr are all two-tailed. However, they can be converted to one-tailed tests by modifying the significance levels. This modification can either be done for an entire document or specific tables in a document.

Modifying the significance levels for the entire document

1. Select a table and from the object inspector , click Appearance > Appearance > Significance > Advanced > Significance Levels.
2. Enter a value into the Overall significance level that is double your desired level. For example, if you want to do a one-tailed test at the 0.05 level (95% level of confidence), enter 0.10 (i.e., 2 * 0.05) into the box.
3. Make appropriate adjustments via cutting and pasting of the Column Letters column in Significance levels and appearance, and, if necessary, adding or deleting new rows by pressing the green + and red - buttons.
4. Select Set as Default.

Modifying the significance levels for a particular table

This is exactly the same as with Modifying the significance levels for the entire document, except that:

1. First, select the tables or pages where the tables are that you wish to modify in the Report section.
2. Select Appearance > Appearance > Significance > Advanced > Significance Levels in the object inspector .
3. Enter a value into the Overall significance level that is double your desired level. For example, if you want to do a one-tailed test at the 0.05 level (95% level of confidence), enter 0.10 (i.e., 2 * 0.05) into the box.
4. Make appropriate adjustments via cutting and pasting of the Column Letters column in Significance levels and appearance, and, if necessary, adding or deleting new rows by pressing the green + and red - buttons.
5. Select Apply to Selection.

Multiple comparison corrections

Generally, one-tailed tests are conducted in situations where there are clear a priori hypotheses regarding the likely results. In such situations, it may be advisable to turn off any Multiple Comparison Corrections in the Statistical Assumptions > Column Comparisons menu.

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How to Apply Statistical Significance in Displayr