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The Content Validity Ratio (CVR) Calculator is a tool used to assess the degree to which an item within a scale or questionnaire is deemed essential by subject-matter experts. It helps researchers refine their instruments by identifying items that contribute to the construct being measured. The CVR is particularly useful in validating tools for educational, psychological, and healthcare research.
Formula of Content Validity Ratio Calculator
The Content Validity Ratio is calculated using the formula:
Detailed Formula Components
- Ne (Number of Experts Indicating Essential):
- The number of experts who rated the item as “essential” during the evaluation process.
- N (Total Number of Experts):
- The total number of experts who participated in the evaluation.
Notes:
- The CVR value ranges from -1 to +1.
- +1 indicates unanimous agreement that the item is essential.
- 0 indicates 50% agreement.
- Negative values indicate less than 50% agreement.
- The acceptable CVR threshold depends on the number of experts and is determine using a critical value table (e.g., Lawshe’s table).
General Terms Table
Below is a reference table based on Lawshe’s critical values, showing the minimum CVR required for an item to be considered valid:
| Total Number of Experts (N) | Minimum CVR (Critical Value) |
|---|---|
| 5 | 0.99 |
| 10 | 0.62 |
| 15 | 0.49 |
| 20 | 0.42 |
| 25 | 0.37 |
This table helps users quickly assess whether an item meets the required CVR threshold.
Example of Content Validity Ratio Calculator
Let’s calculate the CVR for an item evaluated by 10 experts:
- Ne (Number of Experts Indicating Essential): 8
- N (Total Number of Experts): 10
Calculation:
Substitute the values into the formula:
CVR = (8 – 10/2) / (10/2)
CVR = 3 / 5 = 0.6.
Interpretation:
With a CVR of 0.6, the item’s validity is close to the threshold value of 0.62 for 10 experts. Depending on the context, further refinement or discussion with experts might be require.
Most Common FAQs
The CVR threshold is based on Lawshe’s critical values, which depend on the total number of experts. It ensures statistical significance and reliability in determining whether an item is essential.
A negative CVR indicates that less than 50% of the experts considered the item essential. Such items may need to be remove or revise to improve the scale’s validity.
Yes, the calculator can be use iteratively for all items in a scale. Calculate the CVR for each item individually, and then compare the results to identify items requiring adjustments.