Reliability and validity concepts of research

1. Marketing Research
Lecture-5 : Reliability & Validity
Faculty : Ravi Kumar Singh, International School of management Patna

2. Lecture-5 : Reliability & Validity
● Topics to be covered :
● Concept of Reliability
● Concept of Validity

3. Reliability
● Reliability is a measure of the stability or consistency of test scores.
● It as the ability for a test or research findings to be repeatable.
● For example, a medical thermometer is a reliable tool that would
measure the correct temperature each time it is used.
● In the same way, a reliable math test will accurately measure
mathematical knowledge for every student who takes it and reliable
research findings can be replicated over and over.

4. Another example of reliability...
● A doctor uses a questionnaire to understand and diagnose a patient with a
long-term medical problem.
● Several different doctors use the same questionnaire with the same patient
but give different diagnoses.
● This indicates that the questionnaire has low reliability as a measure of the
condition.

5. Types of Reliability
Different types of consistency:
● over time (test-retest reliability),
● across items (internal consistency), and
● across different researchers (inter-rater
reliability).

6. Validity
● Validity simply means that a test or instrument is accurately measuring what it’s
supposed to.
● If research has high validity, that means it produces results that correspond to
real properties, characteristics, and variations in the physical or social world.
● Relation between Reliability & Validity
○ Tests that are valid are also reliable.
○ But, tests that are reliable aren’t always valid.