Relationship between accuracy and validity

A Detailed Explanation on Accuracy, Validity & Reliability - HSC CoWorks

In public health the terms accuracy, precision, validity and reliability mean the following: Simply put: How close a measurement is to the true value Precision: The degree of Link to YouTube video explaining the concepts. To ensure secondary sources are accurate, the information from the site or source must be “The relationship between reliability and validity can be confusing. In this article we discuss: What is an experiment; Validity; Reliability; Accuracy; Relationship between reliability and accuracy.

To ensure that results are reliable: Repetition will only determine reliability it will NOT improve it. A useful analogy is that of a friend arriving on time for appointments. Measurements and other observations can be reliable without being valid. A faulty measuring device can consistently provide a wrong value therefore providing reliably incorrect results.

Accuracy, precision, validity and reliability | communitymedicine4asses

However, measurements and observations cannot be valid unless they are reliable and accurate. Results are accurate if: Accuracy is important by making the experiment as valid and reliable as possible. The experiment should be repeated at least twice i. This ensures that the effect of random errors is minimised or that the outliers can be disregarded or removed.

A Detailed Explanation on Accuracy, Validity & Reliability

Random errors are errors that might affect your experiment the first time you do it, but not the second or third, for example. Random errors may also be present in every measurement taken and be caused by unpredictable fluctuations in the readings of a measurement apparatus, or in the experimenter's interpretation of the instrumental reading.

In any experiment that involves measuring a variable that exhibits natural variation particularly biological variables or environmental factorsthe accuracy of the results will be improved by repetition.

In statistical terms, the mean of the sample will more closely reflect the population mean. The reliability of single measurements is not improved through repetition, but through the design of the experiment. Implementing a method that reduces random errors will improve reliability. However, the entire result of the experiment can be improved through repetition and analysis, as this may reduce the effect of random errors. Summary of reliability The table below provides a summary of reliability.

Repeating the entire experiment gives the same final result. How to improve Through experimental method, e.

Calculating reliability, accuracy and precision - The Chemistry Journey - The Fuse School

How to test Repeat single measurements and look at difference in values. Repeat entire experiment and look at difference in final results. The effect of validity on reliability of an experiment Reliability can be affected by the validity of the experiment.

The difference between accuracy/reliability and validity

However, if an experiment is invalid because the control variables are not constant, then they may be affecting measurements in an unpredictable way, making the result unreliable. Accuracy What is accuracy? Accuracy is much easier to define: The closer it is, the more accurate the experiment. How do you improve accuracy? The accuracy can be improved through the experimental method if each single measurement is made more accurate, e.

Implementing a method that reduces systematic errors will improve accuracy. Accuracy is not precision! Note that, precision is a separate aspect which is not directly related to accuracy. Precision refers to the maximum resolution or the number of significant figures in a measurement.

For example, a clock has a precision of 1 s, whereas a stopwatch has a precision of 0. Whether or not a measurement is accurate does not depend on the precision. How do you test accuracy? You can test the accuracy of your results by: How close the final experimental result is to the accepted value. How to improve Reduce systematic error by calibrating equipment. Improve accuracy of individual measurements.

How to test Compare measurement to value expected from theory. Compare final experimental result to accepted value.