Reliability and Validity – Definition & Types

20.08.20 Reliability & Validity Time to read: 7min

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Reliability and Validity

Reliability and validity are two important concepts that are often relied upon by college students looking to determine the research quality. Below is a more detailed look into the two concepts, including their basic definitions and how they are assessed. You will also learn ways you can use to guarantee reliability and validity when conducting research.

Reliability and Validity - FAQ

Reliability and validity are considered to be crucial factors in any research study. Combined, they allow the student to obtain results that are both firm and beyond reproach. Furthermore, researchers also use them to assist in generalizing their findings for a bigger population. In return, the results can be applied in a real-life scenario to help in improving different aspects of the population’s lives. After completing your academic work you can use our online printing services for printing and binding your paper.

Validity aims to tell you whether a test is suitable for a situation you may have in mind. Reliability, on the other hand, seeks to inform you whether a score attained on the same test is trustworthy or not. In short, you can’t get a valid conclusion from any test score without being certain about the reliability of the test.
Just because a test is deemed reliable doesn’t imply that it’s going to be valid. So, does reliability affect validity? YES, it does!

The main difference between reliability and validity lies in what each term means, or what it refers to:
Reliability implies the limits to which a particular tool used in the assessment process can yield constant results, even after taking repeated measurements.
On the other hand, validity is used to discuss the degree to which the research instrument measures will get to measure the objects or items the student researcher has in mind.

Validity, unlike reliability, is based on judgment. It’s a level to which your attained test scores are able to represent their intended variables truly. What this means is that reliability is consistent across researchers, across items, and across time.

As earlier mentioned, it’s possible for a test to be reliable, implying that all those taking the test are likely to get a similar score regardless of where or when they sit for it (but within reason). However, this isn’t to imply that the test is capable of measuring what it seeks to measure or even that it’s valid. Therefore, the test can be reliable, but at the same time, remain invalid.

Reliability and validity: Definition

Reliability and validity are often considered as the two needed qualities of any given measurement instrument or procedure. It’s essential to note that there doesn’t exist a perfect validity or reliability. While it’s possible to think of certain measures as being accurate, the reality is that all measures will contain one or more sources of error.

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How Are Validity and Reliability Assessed?

It’s possible to estimate reliability by comparing varied versions of a single measurement. It’s, however, going to prove a bit difficult to assess validity, which you can estimate by comparing the results attained to other existing theories or relevant data. The methods used to estimate reliability and validity falls into different types:

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Reliability and Validity: Types of Reliability

You can estimate different kinds of reliability using numerous statistical methods:

1. Test-Retest
It’s a type of reliability used to assess the consistency of a given measurement across time. It seeks to establish whether a tester will obtain the same results if they repeat a given measurement.

2. Internal Consistency
It is used to assess the reliability of the dimension in question. The question here is whether you will attain the same results if you pay attention to separate fragments of an experiment that have all been designed to measure a similar thing.

3. Interrater
In reliability, this is used to check the uniformity of a result through several observers or raters. It seeks to determine whether a researcher will get to obtain the same set of results where different individuals get to carry out the measurement.

Reliability and Validity: Types of Validity

You can estimate a measurement’s validity based on three kinds of evidence. Respectively, each type of evidence can be appraised via statistical or expert judgment methods.

1. Criterion
It seeks to measure the limit to which a result obtained after a measure relates to any other valid measure used for the same concept.

2. Content
It’s used to evaluate the limit a measurement gets to cover every single aspect of the concept under evaluation.

3. Construct
It’s a type of validity that seeks to assess how far a measure adheres to existing knowledge and theory of a concept under measurement.
For a researcher to evaluate the validity of any cause-and-effect association, they will have no option but also study internal validity. It’s a type of validity used to assess the experiment’s design. External validity refers to whether the results can become generalized.

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How to ensure Reliability and Validity

Reliability and Validity: Ensuring Validity

Researchers that use ratings or scores to measure variations, e.g., in physical properties, ability levels, and psychological traits, should ensure the results are a reflection of the true differences. It’s essential to consider validity from the early research stages, i.e., when deciding on how to go about the data collection process.

1. Choose the Right Measurement Methods
Confirm that your data collection and the measurement method is top-notch, and that’s intended to measure the exact thing you would like to learn. All your measurement methods ought to be well researched and proven to be based on existing information.

2. Utilize the Correct Sampling Techniques
For you to generate results that are valid and easily generalized, begin by accurately defining the population, you would like to sample. The definition can be on a profession, geographical location, or even on a given age range. While at it, confirm your participants are enough and that they provide a good representation of your target population.

Reliability and Validity: Ensuring Reliability

Reliability is something you will need to consider throughout the whole process, especially when collecting data. Whenever you are using a technique or a tool to gather the data, you ought to confirm that your results are reproducible, stable, and precise.

1. Consistently Apply the Methods
Carefully plan your methods to ensure you get to follow the same set of steps for every measurement. This is particularly important for a process involving multiple researchers.

2. Standardize the Research Conditions
As you are collecting data, you will need to make sure the circumstances get to remain as consistent as you can. Consistency assists in reducing the influence of external factors, which are likely to play a role in creating a variation in your results.

Where to write about Validity and Reliability

Researchers need to confer reliability and validity in different parts of their dissertation or thesis statements. They need to show that they accounted for them when planning their research. The same must also be done when interpreting the results of their research. It helps to make the research project more trustworthy and credible.

Reliability and Validity in Your Thesis

Section What to Discuss
Literature Review Here, you need to discuss what other people in this field have done to improve or devise valid and reliable methods.
Methodology State how you planned the research process to guarantee the reliability and validity of all measures employed. Make sure to note the sample set, preparation, measuring techniques, and external conditions.
results In case you get to calculate reliability and validity, ensure these values are stated together with the results attained.
discussion Use this section to discuss what makes your results reliable and valid. Ensure you comment on whether the results you attained were consistent and if you were able to reflect the correct values.
conclusion If you had a hard time proving the reliability and validity of your results, make sure to note that in this section.
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In a Nutshell

  • Researchers don’t assume that their preferred measures work. Research is needed to prove they do.
  • Reliability and validity are the two criteria used by researchers to evaluate research measures.
  • Validity refers to a judgment pegged on several kinds of evidence. Any evidence to be considered should cover the reliability of the measure.
  • The reliability and validity of a measure can only be established by observing a pattern of results obtained from more than one study.