Alpha if the item is deleted: what it means and how to read it
In the report: alpha if deleted — The alpha (or the standardized alpha) of the remaining items without this one.
How to read it
Higher than the alpha of the whole scale — the scale is more reliable without this item: check whether it is reversed or off-topic.
In plain words
A teacher's quiz of 7 questions had an alpha of only about 62 parts of 100, lower than she hoped. She wanted to know whether one question was spoiling it. For each question the report showed the alpha if the question is deleted: how well the other 6 hang together without it. For question 5 it came out 0.81, about 81 parts of 100, and for every other question it stayed near 60. Now she can answer: without question 5 the rest hang together much better. She checks whether question 5 was asked the opposite way around or is about something else.
Example
The cell with alpha if deleted is selected in each report; point at a label to see its note.
- — the sample data (50 rows) the examples use
- — all columns starting with q; includes 'if item deleted'
=STATS_ALPHA(Data!A1:T51, "/^q/", TRUE)
Where you see it
STATS_ALPHA— Computes Cronbach’s Alpha — a measure of internal consistency (reliability) for a set of items, such as Likert-type questions.
Related values
- Corrected item-total correlation — The correlation of the item with the sum of the other items (the item itself left out of the sum), as SPSS RELIABILITY "Corrected Item-Total Correlation". Empty for an item without spread.
- Cronbach’s alpha — Cronbach’s alpha: how consistently the items measure the same thing, on the rows where every item is answered.
- Standardized alpha — Alpha from the mean correlation of the items, as SPSS "Based on Standardized Items": as if every item had the same variance.
Get it in your sheet
One formula in a cell gives the whole report, Alpha if the item is deleted included. ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)