Question

Say you ran a protein sample of unknown concentration four times using the Bradford assay and you find its concentration is 3.3, 3.1, 3.0, and 3.0 mg/mL for trials #1 through #4, respectively. Likely you would conclude these measurements

a. are precise.

b. are accurate.

c. lack precision and accuracy.

d. lack precision, but are accurate.

Answer: Choose an item.

Give an explanation for your choice for Question #7 above

Answer 1

The correct option is a) are precise.

a. are precise- the measurements given here are precise. This is because these measurements are close in value to each other, even when their accuracy is not known when conducted four times under the same conditions. Repeatability is an important feature of precision, where variations in the readings occur due to minor errors when using the same set of instructions and types of equipment.

b. are accurate- a measurement is said to be accurate when it is close in value to the true/original/standard value. Here in the question since a standard has not been mentioned, we can not say whether it is accurate.

c. lack precision and accuracy- when the values are neither close to the true value nor is close to each other in terms of repeatability.

d. lack precision but are accurate- this occurs when the values are close to the original standard measurement, but within themselves, they are not close in values and are significantly away.