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How to Calculate Mean & S.D. for Likert-Scale Questionnaires (with 5-Level Interpretation)
Once your survey data is collected, the key step in Chapter 4 (Results) is computing basic statistics — the mean and standard deviation (S.D.) — to describe your data.
1. Arithmetic Mean (x̄)
The sum of all scores divided by the number of respondents. It tells you the overall opinion of the sample toward each item.
2. Standard Deviation (S.D.)
- Low S.D. (near 0): respondents answered similarly (consensus).
- High S.D. (above 1.00): opinions differ widely.
3. Five-Level Interpretation (Best, 1977)
Each interval spans (5 − 1) / 5 = 0.80:
- 4.21 – 5.00: Highest
- 3.41 – 4.20: High
- 2.61 – 3.40: Moderate
- 1.81 – 2.60: Low
- 1.00 – 1.80: Lowest
Computing this item by item in Excel is slow and error-prone. Our free tool computes the mean and S.D. per item, applies the interpretation automatically, and drafts the report text for Chapter 4.