Content validity refers to the extent to which the items of a questionnaire accurately represent the concept or construct they are intended to measure. In simple terms, it assesses whether the content of a tool is aligned with its intended purpose. This type of validity is typically evaluated by a panel of experts who review each item for relevance, necessity, clarity, and simplicity. Ensuring strong content validity is essential in the early stages of tool development, especially in fields like medicine, psychology, and social sciences. Without establishing content validity, a questionnaire may fail to capture the full scope of the construct, leading to incomplete or misleading research outcomes. Thus, content validity serves as a foundational requirement for creating reliable and meaningful measurement instruments.

The Content Validity Ratio (CVR) is one of the key quantitative indicators used to evaluate the content validity of a questionnaire. It measures how essential each item is from the perspective of a panel of experts. In this method, experts are asked to classify each item as “Not necessary,” “Useful but not essential,” or “Essential.” Based on their responses, the CVR is calculated to determine the proportion of experts who consider an item essential for measuring the intended construct.

A higher CVR value indicates stronger agreement among experts regarding the necessity of the item. According to Lawshe’s table, each item must exceed a specific threshold (e.g., 0.49 for 15 experts) to be considered statistically valid. If an item’s CVR is below the minimum acceptable value, it may need to be revised or removed. By calculating CVR, researchers can identify weak or irrelevant items and enhance the overall content validity of their instrument.

To calculate the Content Validity Ratio (CVR), you first need a panel of experts—usually between 5 and 20 individuals—who will evaluate each item of the questionnaire in terms of its necessity. Each expert is asked to rate every item using one of the following three options:

1- Not necessary 2- Useful but not essential 3- Essential

Next, count the number of experts who selected “Essential” for each item (this number is denoted as Ne). The CVR is then calculated using the following formula:

In this formula, N represents the total number of experts. The resulting CVR value is compared with Lawshe’s critical value table. For instance, if you have 15 experts, the minimum acceptable CVR value is 0.49. If an item’s CVR falls below this threshold, it is considered to lack sufficient content validity and should be reviewed or possibly removed. This method allows researchers to identify which items are statistically necessary based on expert consensus, ensuring that the final questionnaire is both focused and meaningful.

The acceptable value of the Content Validity Ratio (CVR) depends on the number of experts involved in the evaluation and should be interpreted using Lawshe’s critical value table. As the number of experts increases, the minimum required CVR slightly decreases. For instance, with 15 experts, the minimum acceptable CVR is 0.49. If an item’s CVR falls below this threshold, it is considered to lack sufficient content validity and may need to be revised or removed. Therefore, when analyzing CVR results, it is essential to compare the calculated value against Lawshe’s reference table to make informed decisions about which items should be retained or discarded.

The Content Validity Index (CVI) is a key quantitative measure used to assess how well each item in a questionnaire aligns with the intended construct. Unlike CVR, which focuses on the necessity of an item, CVI evaluates the relevance, clarity, and simplicity of each question from the perspective of subject matter experts. Experts rate each item on a four-point scale—from “not relevant” to “highly relevant.” The CVI is then calculated as the proportion of experts who rate the item as either 3 or 4. If this proportion exceeds 0.79, the item is considered to have acceptable content validity. CVI helps researchers identify items that may be confusing, poorly worded, or misaligned with the research objective, making it an essential tool for refining and validating questionnaires.

To calculate the Content Validity Index (CVI), you must first provide the questionnaire to a panel of expert reviewers. Each expert is asked to evaluate every item based on three criteria: relevance, clarity, and simplicity, using a four-point scale (1 = not relevant to 4 = highly relevant). After collecting the ratings, count how many experts gave a score of 3 or 4 for each item. Then, divide that number by the total number of experts to obtain the CVI for that item. For example, if 12 out of 15 experts rated an item as 3 or 4, the CVI would be 0.80.

Items with a CVI above 0.79 are considered acceptable, those between 0.70 and 0.79 may require revision, and items below 0.70 are usually recommended for elimination. This process is repeated for every item to ensure that each part of the instrument is relevant, well-worded, and aligned with the overall goal of the study.

CVI Formula in Content Validity

This blog post is based on the following source:

Madadizadeh, F., & Bahariniya, S. (2023). Tutorial on how to calculating content validity of scales in medical research. Perioperative Care and Operating Room Management, 31, 100315. doi – Download file