In: Psychology
1. What is the major difference between reliability and validity? Is it possible to have a scale that is reliable, but not valid? If so, how?
While doing any experiment we must have both reliability and validity. Then only we will have some idea about perfectness of our resutls in experiment.
1. What is the major difference between reliability and validity?
Reliability indicates the consistency in output results of an experiment. If results of an experiment are same each time measured then that characteristic of the experiment is called reliability.
Validity indicates wellness of the process we have followed while doing an experiment. If no errors decided our results but only independent variable decided our results then that is called validity.
This is the main difference between reliability and validity.
Is it possible to have a scale that is reliable, but not valid?
Yes, it is possible to have a scale that is reliable but not valid.
If so, how?
Some times the same mistake can be done by the experimenter while doing the experiment each time. He is committing the same mistake so that he will receive consistent results. Results are consistent, so that there is reliability. But there is flaw in that experiment, so that there is no validity.
Example: A weighing machine initially didn't set to the 0 ( zero). Then if we try to calculate weight of anything, we will have reliability but no validity.