Why is reliability important?

Blog (4th )

Why is reliability important?

What is reliability? (In statistics) Reliability is the consistency of a measure, often used to describe a test. A test is considered to be reliable if the researchers get the same/very similar results repeatedly. It is not possible to calculate reliability exactly, however there are different ways that we could estimate and/or increase the reliability of one test.

Reliability is very important to psychological tests, so does to our general life. Businesses would need to get reliable supplier, would need to ensure the reliability of their products…etc.  To attract new consumers and maintain the loyal consumers so their businesses could keep running and growing.

Here is a video talking and explaining why is reliability so import? (To the businesses and their logistics department)

In the video,The heads of Logistics of Tetra Pak, Addidas, M&S stated they really need everything is to reliable and they could not/do not want to afford the cost of something being not reliable.
And to the businesses, reliability is really important because they need to maintain/grow their Reputation, Customer Satisfaction, to reduce the Warranty Costs to the lowest, to meet Customer Requirements that are increasing by time, and to keep a Competitive Advantage.  In order to test the reliability of the product many businesses would hire a group of people to analysis it, for example RAL (stands for Reliability Analysis Laboratory). https://www.reliabilityanalysislab.com/homepage.asp

Back to Reliability in psychology/statistics, if your data from the test is not reliable, there is no point to publish it; it means the test must have something wrong, and for sure it cannot generalise to the whole or other populations. Reliability usually linked with Validity, Validity is the extent to which a test measures what it is supposed to measure. For the test to be valid it must be reliable; but reliability does not guarantee validity. All measurement procedures would have some potential errors (random error and/or systematic error), the aim of reliability is to reduce and minimise it. The most common types of reliability are test-retest reliability, inter-rater Reliability parallel-form reliability, and internal consistency reliability. Test-Retest Reliability is used to assess the consistency of a test/measure arcoss time. Inter-Rater Reliability is used to assess the degree to which two or more different raters give consistent estimates of the same test, the scores would then be compared to determine the consistency of the raters estimates. Parallel-Forms Reliability is used to assess the consistency of the results of two different tests created in the same content domain. Internal Consistency Reliability is used to measure the consistency of results across items within a test. http://changingminds.org/explanations/research/design/types_reliability.htm
This is a website explaining different types of reliability in a simple way.

However, at some extent reliability might become not as important as I have mentioned above, considering Freud’s theory about personality, it is not quite reliability and valid(at least to me). He suggested there are three elements of personality–known as the id, the ego and the superego–work together to create complex human behaviors. Basically, Id is the evil side of yourself,  Ego is the balance, and superego is the angel side. Whereas I do not think this would applied to me and some people, however this theory has been used a lot from the the 1920s till now. Therefore, there are always some special or different cases.


To explain why there are a lot of different ways to estimate/increase reliability of one test, it is because reliability is really important to a test and researchers would definitely love to get their research to the maximum reliability and validity.

In conclusion, reliability is important. Reliability is one of the most important elements of test quality. It has to do with the consistency, or reproducibility, of an examinee’s performance on the test. It would be representative if the test were reliable.

This entry was posted in Psychology weekly blog. Bookmark the permalink.

3 Responses to Why is reliability important?

  1. psuc6b says:

    Hi, I really enjoyed watching the video you provided here and I think it illustrates you point nicely. It would be interesting to relate this idea to examples in the field of psychology. For example, testing how good people perform in memorising familiar names would require a high amount of reliability. Cohen and Burke conducted a study (1993) in which they looked at the ability of individuals to remember names. They could differentiate between the mentally healthy and those who were suffering from memory loss due to ageing or aphasia, because the measures of mentally healthy individual’s score built an average with a low amount of error. In this particular research area, mean scores determine whether someone has a deficient memory. This is why it is important that the study be replicated numerous times and hence made reliable.

    Reliability is the idea that results, no matter how many times or by who they are replicated, should always be the same. Eyewitness testimony is often considered highly reliable in Court. And rightly so according to Yuille and Curtshall, who believe that level of accuracy and ability to remember detail is increased in a traumatic scene. However psychological studies found that the following factors may deform the witness’ view and memory of an event: stress/anxiety, reconstructive memory, weapon focus and leading questions (Loftus &Palmer). So there is an argument here that reliability may be subjective, in particular in qualitative studies.

  2. psuc3d says:

    Hello! Really great blog. The only thing I would have liked you to expand on is the idea that if something is reliable, it is not necessarily valid. (Here is a link describing this http://www.psychology.sunysb.edu/attachment/measures/content/attachment_validity.html). This is an idea that I stuggled with for a long time until my A-Level teacher told us to imagine using the size of someone’s head as a measure for their intelligence. The results would be very reliable (because the participants’ heads wouldn’t change size and neither would their intelligence) but it is VERY unlikely that it would be reliable! Look forward to reading your next blog. Happy Holidays!

  3. Pingback: Homework for my TA- week 11 « psuc6b

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s