Question

Differentiate between the following pairs of words as used in study designs:
a. Precision and Accuracy
b. Validity and Repeatability, using a maximum of 300 words

Answer 1

(a)

Precision and Accuracy-

• Accuracy is closeness of the measurements to a specific value, whereas precision is the closeness of the measurements to each other.
• Accuracy of a set of measurements is the degree of closeness of those obtained measurements of a particular quantity to the true value of that quantity.
• The precision of a set of measurements is the degree to which performed repeated measurements under identical conditions show the same results.
• A measurement is accurate if we obtain value close to the true value. A statistical estimate is more accurate if we obtain estimated value closer to the true population parameter. In this case, error is to be minimized as much as possible.
• A measurement is precise if we get close values through measurements done again and again. A statistical estimate is more precise if we get closer values through estimates using different samples again and again. In this case, variance is to be minimized as much as possible.

Thus we can say that accuracy of measurements implies precision but converse is not always true.

​​​​​​(b)

Validity and Repeatability-

• Validity is the extent to which a certain conclusion or measurement is well-founded and likely corresponds accurately to the real value.
• Repeatability is the closeness of the agreement between the results of two consecutive measurements of the same item which are carried out under unchanged conditions of performing measurement.