Reliability vs. Validity in Research – Overview and Comparison

02/20/2020 | George Orwell | 408

Reseracer has design Overviewing 

Reliability and validity represent the effectiveness of the different methods applied in investigation. They are basically two crucial parts of the research. There is a direct relationship between reliability and validity. The reliability of the pr
used for measuring outcome is very much important in order to make the investigation to be valid.

Reliability mainly is the level measures that are consistent. Whereas, validity represents the degree up to which different methods used produce accurate results. It is very much essential for you to think about the reliability and validity of the study while making choice of research design or selecting different techniques for performing investigation.

Comparison between reliability and validity

There is a significant difference between reliability and validity of the research:

Difference between assessment procedure of reliability and validity here is also a great difference between the way different types of reliability and validity are : 

  • Assessment procedure of measuring the different types of reliability
Basis Validity Reliability


Validity basically is considered to be a circumstance when the specific tool is correctly measuring the thing which it is expected to measure.Reliability can be defined as the level up to which specific test able to generate the same results or not when it is repeated.


The valid tool is considered to be as reliable.An instrument or tool which is reliable cannot be considered to be as valid.

Role in evaluation

Validity plays a very important role in evaluation.Reliability has no role to play in the evaluation procedure.


Measuring the validity of the study is one of the complex and hard tasks.        It is quite an easy task to measure reliability.


Validity mainly concentrates on checking whether a specific tool has generated an expected outcome or not.It mainly focuses on analyzing the way a specific instrument producer’s consistent outcome.

Techniques for improvements

For improving the validity of research you are required to clearly define your objectives.
You need to  engage respondents in the investigation procedure·Selection of the right methods for measurement is very much essential.
·Making the choice of the right sampling technique for selecting participants is very much important. You are required to clearly define your population. 
·You are required to  include relevant questions

·You should create a proper environment for performing the test. It is always advisable to execute tests in a natural setting.

·Consistency in the method is very much necessary for increasing reliability.

·Controlling the situation is crucial for increasing reliability.


If you are measuring the temperature of the water, the instrument used shows different result every time beside you have taken all initiatives to control the temperature, you close down the knob of gas after that also next time when measurement is taken thermometer represents the same result.  Therefore, it is assumed that the thermometer is not functioning properly and the measure is considered to be as invalid.For example, the temperature of hot milk is measured in the same situation and thermometer also shows the same result every time, therefore the result can be considered to be as highly reliable.

Types of reliability

Things to be assessedExample

Test-retest reliability

It includes the measurement of consistency over a period of time.

This means that the measurement tool which you are using generates the same result when a specific test is repeated.

Investigation performed for measuring the level of job satisfaction among employees. Employers were provided with a questionnaire where they have provided their responses. After a week the same questionnaire has been distributed and the same answers were given by participants, it shows high reliability.

Inter-rater reliability

It refers to the extent the outcome remains consistent when  different researchers perform the same measurement i.For example,Different teachers check the cardiology Exam paper of one student. And every teacher has allotted different marks to students in a particular subject which represents low inter-rater reliability.  As every teacher has applied different criteria for checking the exam paper.

Internal consistency

It can be defined as extending up to which specific measurement is consistent in itself.For instance, Investigator has design A questionnaire for measuring the level of motivation in employees. If you   categorize outcome into two parts it should represent the powerful correlation between two different outcomes. If in case there is no correlation between results it represents low internal consistency.

Forms of reliability

 Assessment factor Example


Observation done through using specific measure  matches your knowledge about a particular concept. Researcher has design the questionnaire  for measuring the level of motivation in workers.  You can analyze motivation  by evaluation of other related characteristics such as Self-confidence, work knowledge, etc. As there is a powerful correlation between the above traits and level of motivation among employees which represents highly construct validity?


 researcher is measuring Level up to which particular technique able to cover the different facet of idea. Researcher has design  A special test  for measuring the student’s level of English in terms of speaking, writing, and understanding. According to the experts, understanding is also important while judging the student English language skill.


Degree up to which outcomes of specific measurement is related to other suitable measures of similar thought.Researchers conducted for analyzing the people’s opinion about the particular political party if in case the findings of the investigation match with the actual result of election this will indicate high criterion reliability.
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