To reverse a scale, you subtract each value from a reference point, which is typically one value above the maximum value on your original scale.
Understanding Reverse Scales
Reverse scales are commonly used in surveys and questionnaires to reduce response bias (like acquiescence bias, where respondents tend to agree with statements regardless of content). By reversing some questions, you force respondents to think more carefully about their answers.
The Formula
The formula for calculating a reverse scale is:
- Reversed Value = (Highest Value + 1) - Original Value
Or, if your scale starts at zero:
- Reversed Value = Highest Value - Original Value
Examples
Here are a few examples to illustrate how to calculate reverse scales:
Example 1: Scale from 1 to 5
Suppose you have a scale from 1 to 5, and you want to reverse a score of 2.
- Identify the highest value: 5
- Add 1 to the highest value: 5 + 1 = 6
- Subtract the original value from the result: 6 - 2 = 4
So, a score of 2 on the original scale becomes a score of 4 on the reversed scale.
Example 2: Scale from 0 to 6
Suppose you have a scale from 0 to 6 and you want to reverse a score of 0.
- Identify the highest value: 6
- Subtract the original value from the result: 6 - 0 = 6
So, a score of 0 on the original scale becomes a score of 6 on the reversed scale. A score of 6 becomes 0.
Example 3: Scale from 1 to 7
Suppose you have a scale from 1 to 7 and you want to reverse a score of 5.
- Identify the highest value: 7
- Add 1 to the highest value: 7 + 1 = 8
- Subtract the original value from the result: 8 - 5 = 3
So, a score of 5 on the original scale becomes a score of 3 on the reversed scale.
When to Use Reverse Scales
Reverse scales are particularly useful in:
- Surveys and questionnaires: To reduce response bias.
- Psychological testing: To measure attitudes or opinions.
- Data analysis: To ensure that all variables are oriented in the same direction for easier interpretation.
Considerations
- Clearly Label Reverse-Coded Items: When using reversed scales, clearly indicate which items have been reverse-coded so that users can understand and correctly interpret the data.
- Data Cleaning: Always double-check your data after applying reverse coding to make sure the calculations have been performed correctly.
In summary, reversing a scale involves subtracting the original value from a constant (usually one more than the highest scale value or simply the highest scale value if your scale starts at zero) to reorient the data. This is a valuable technique for improving data quality in various research and analytical contexts.
