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Reliability and Validity

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Reliability and Validity

Imagine you are bowling one night, and every time you take a turn, you miss all of the pins. While you do not score a single point the whole night, you still have a reliable outcome due to your consistent losses. This is just one example of how something can be reliable but not valid. If you knocked down all the pins every time you went up, this would display both reliability and validity because you constantly achieved the goal intended for the game.

In the scientific method of psychological research, both reliability and validity are essential when utilizing any tools of measurement or tests. This text will define both terms, indicate their differences, and explore common issues in the scientific investigation regarding reliability and validity.

  • What are reliability and validity?
  • What are issues with reliability and validity?
  • How are reliability and validity used in research?
  • What are examples of reliability and validity?

Meaning of Reliability and Validity

At first glance, you may think these terms have very basic definitions; however, each of their meanings can be increasingly intricate and significant in terms of psychological research. Both concepts are fundamental to understand when learning about experiments and the scientific method.

Reliability

In terms of scientific investigation, the definition of reliability is the presence of a stable and constant outcome after repeated measurement (Jackson, 2014). To put it into perspective, think of any form of psychological research using tests to measure specific outcomes. A test that is considered reliable will show similar outcomes each time it is administered. This consistency and dependability add value to the tests being used in research.

Validity

Validity is the term used to describe the indication that a test or tool of measurement is true and accurate. In other words, a valid test or tool is measuring the exact unit that it states to measure. There are examples of validity in day-to-day life. Think of a driver's license and how it is only valid if all the information about the driver is true and accurate. In psychology research, a test can only be considered valid if the outcome is accurate to what the test claims to measure.

Reliability and Validity, examples showing valid and reliable outcomes and their combinations, StudySmarterReliability and validity, wikimedia.org

Issues with Reliability and Validity

Within the domain of psychological research methods, any errors in the reliability and validity of a test or experiment are very detrimental to the value of the research. Before any scientific article, journal, or experiment can be posted, the findings must first meet standards of both reliability and validity. Unfortunately, instances in which these standards are not met may lead to unethical research and false or misleading claims.

Thalidomide Tragedy

During the 1950s and 60s, Thalidomide was thought to be a cure for nausea in pregnant women; however, it caused critical congenital disabilities in infants (Kim, 2011).

This is just one devastating example of what can happen once certain study standards are compromised. These significant moments in the history of scientific research put an emphasis on the importance of reliability and validity in the realm of scientific investigation.

Errors in Reliability

There are common errors made in psychological research methods that may impact the reliability of a study. These types of issues include:

Method Error

A method error can occur due to the experimenter's actions or the testing atmosphere.

Questions asked about method error include:

  • Is the experimenter using the tool of measurement correctly? Is the tool functioning properly?

  • Is the environment of the test affecting the outcome of the measurement?

Trait Error

In trait errors, issues of reliability stem from the actual subjects of the experiments.

Questions asked about trait error include:

  • Is the subject using biased actions or answers?

  • Are they feeling well?

    • A subject who is feeling unwell may not perform as they would usually, thus affecting the outcome and reliability of the study.

Imagine a test is administered to measure athleticism in various sports teams; however, one of the tested teams had food poisoning the same day. This could interfere with the reliability of the results.

Errors in Validity

Similar to the issues within reliability, certain types of errors in research may also jeopardize the experiment's validity. A few of these errors are known as:

Maturation

Maturation may affect the validity of an outcome of long studies. Could the passage of time interfere with the initial performance of the test? How might a participant or test be affected during this time allotted?

Biases

Biases that may occur in the selection of participants may negatively impact the validity of the study. When the selection of the participants happens under bias, the ability for the study's outcomes to be generalized amongst a population becomes disabled.

Interaction Effects

Interaction effects can impact the validity in cases where there are pretests or multiple tests involved in one study. The application of a pretest can interfere with another measurement or test that follows.

Consider a test that aims to measure reading comprehension. The test taker is asked to read five articles in one session. Each piece is ten pages long. The validity of results regarding their comprehension may be affected due to factors caused by the application of multiple lengthy articles.

As you can see, many issues can influence the value and credibility of any scientific investigation or study. Analyzing the errors that may decrease the reliability and validity of research is one of the highest priorities in the scientific method.

Reliability and Validity in Research

The scientific method is applied in all facets of scientific research and investigation. This process employs rigorous empirical methods to get a reliable and valid outcome. There are several examples of reliability and validity in psychology research methods. Assessing these examples will help you better understand the type of reliability and validity for each situation in psychology research.

Examples of Reliability and Validity

There are four types of reliability in psychology research, all of which indicate levels of consistency in various situations. The three types of validity measure the truthfulness and accuracy of tests in many different ways.

Test/Retest Reliability

This type of reliability in research tests the consistency of results over time by administering the same test more than once.

Alternate-Forms Reliability

By using multiple forms of similar tests, a researcher can indicate whether the measurement is reliable depending on the consistency of an outcome. This is why the method is named alternate-forms.

Split-Half Reliability

This is when a study splits the test into two parts and measures the stability between measurement items in both test halves. While this does not account for the consistency over time, it does measure the reliability of the content within the test itself.

Interrater Reliability

This refers to measuring reliability by assessing the consistency of observations across raters/judges.

You can distinguish the differences between the types of reliability through their names! (i.e Interrater = reliability measured in-between raters)

Content Validity

A test with content validity aims to measure the relevance across all content/ items within the given test, not just in one area.

Criterion Validity

The analysis of the accuracy of a test in predicting the abilities or outcomes of participants.

Construct Validity

One of the most important forms when measuring validity is construct validity. This is because it is one of the most utilized in psychology as it analyzes the extent to which a test measures the construct it claims to measure.

Within qualitative research methods, validity and reliability can be determined through the consistency and objectives of the data outcomes, participants, types of tests, and researcher observations.

Reliability and Validity - Key takeaways

  • Reliability is the presence of a stable and constant outcome after repeated measurement and validity is used to describe the indication that a test or tool of measurement is true and accurate.
  • Common issues in reliability include measurement errors like trait errors and method errors.
  • Issues in validity are maturation, biases, and interaction effects.
  • Four types of reliability are test/retest, alternate-forms, split-half, and interrater reliability.
  • Construct validity is very prominent in the field of psychology research. It analyzes the extent to which a test measures the construct it claims to measure.

Frequently Asked Questions about Reliability and Validity

Reliability is the presence of a stable and constant outcome after repeated measurement or test. Validity is an indicator that a test or tool of measurement is true and accurate.

Reliability and validity are very important because without them, research would not be considered valuable and could lead to false claims or misinformation.

Validity and reliability are determined in qualitative research through the consistency and objective of the data outcomes, participants, types of tests, and observations of the researcher.

Issues in reliability and validity can occur through biased participants, method errors, effects of interaction, and maturation.

The four types of reliability in psychology research are test/retest reliability, alternate-forms reliability, split-half reliability and interrater reliability. The three types of validity are content validity, criterion validity and construct validity.

Final Reliability and Validity Quiz

Question

What is the definition of Reliability?

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Reliability is the presence of a stable and constant outcome after repeated measurement or test

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What is the definition of Validity?

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Validity is an indicator that a test or tool of measurement is true and accurate.

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What is the importance of Validity and Reliability in terms of research?

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 They indicate whether a measurement is consistent, accurate, and trustworthy. All of which, add value to the research.

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What are two errors of Reliability?

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Method error and trait error.

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What is the issue of Maturation?

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The passage of time in an experiment interferes with the Validity of the measurement.

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What is the bias issue in validity?

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Bias in the selection of participants made by the researcher may affect the validity of an outcome.

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What is an interaction effect in validity?

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multiple tests before one another can negatively impact the outcome of a test that follows.

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Method error is: 

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An issue of reliability stemming from the experimenter or tool of measurement

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Trait error is:

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an issue of reliability that stems from the actions or behavior of a participant/subject

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Can something be Reliable but not Valid?

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yes

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Question

Anne is playing a game of darts. She throws all of her darts on the lowest scoring area of the board every single turn and loses the game. Were the shots taken by Anne reliable or valid? Explain.

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Reliable but not valid. Because Anne consistently hits the same area each turn, it is reliable. Anne failed to achieve the goal of the game by hitting the center of the board, therefore it was not valid.

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You step on a new weight scale and see an accurate number on the scale of how much you weigh. You step on the scale 4 more times and get a completely different weight every time. Valid or Reliable? Why?

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The scale was Valid once for reading a correct weight; however, because the result was not consistent it is not a reliable measurement.

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List the 4 types of Reliability

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  1. Test/retest
  2. Alternate-forms
  3. Split-half
  4. Interrater

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List the 3 types of Validity

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  1. Content
  2. Criterion
  3. Construct

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What Scientific process is used in all research?

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The Scientific Method

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What is reliability?

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Reliability is a way to measure something and get consistent results.

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What is validity?

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Validity is how accurate something that measures, can actually measure what it means to measure.

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How many different reliability/validity types of measurements can there be from a research study?


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There can be four different result types from a research study.

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What are the four different reliability/validity types of measurements that can come from a research study?


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Reliable and valid, reliable and not valid, not reliable and valid, not reliable and not valid.

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What does it mean for test results to be reliable and valid?


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In this, the results are considered reliable, giving consistent results, and they are considered to be valid, meaning that something is accurately measuring something else.

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What does it mean for test results to be reliable, but not valid?


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In this, the results are considered reliable, giving consistent results, but they are not considered to be valid, meaning that something is not accurately measuring something else.

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What does it mean for test results to be not reliable, but valid?


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In this, the results are considered not to be reliable, giving inconsistent consistent results, but they are considered to be valid, meaning that something accurately measures something else.

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What does it mean for test results to be not reliable and not valid?


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In this, the results are not considered reliable, giving inconsistent results, and they are not considered to be valid, meaning that something is not accurately measuring something else.

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What are the two types of errors in reliability?


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The two types of errors in reliability are random errors and nonrandom errors.

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What is the one type of error in validity?


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The one type of error in validity is a systematic error.

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What happens when a random error occurs?


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Random Errors occur when something by chance (randomly) affects the ability to get an accurate measurement. When more random errors are present, it results in a less reliable result.

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What is a nonrandom error?

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Nonrandom errors are more of a systematic error, and can also affect the validity of a test.

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When do systematic errors occur?


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Systematic errors occur due to different factors that systematically influence the measurement process.

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True or False: It is important to have reliable and valid test results.

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True

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True or False: A thermometer that gives faulty readings over and over would be considered a systematic error.

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True

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True or False: A test that is considered reliable will show similar outcomes each time it is administered. 

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True 

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Fill in the blank: __________ is the term used to describe the indication that a test or tool of measurement is true and accurate. 

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Validity

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True or False: A valid test or tool is measuring the exact unit that it states to measure.

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True 

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Fill in the blank: In psychology research, a test can only be considered ______ if the outcome is accurate to what the test claims to measure. 

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valid

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True or False: Before any scientific article, journal, or experiment can be posted, the findings must first meet standards of both reliability and validity.  

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True 

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Fill in the blank: A ________ error can occur due to the experimenter's actions or the testing atmosphere.  

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method 

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Fill in the blank: In _____ errors, issues of reliability stem from the actual subjects of the experiments.

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Answer

trait 

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True or False: When the selection of the participants happens under bias, the ability for the study's outcomes to be generalized amongst a population becomes disabled. 

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True 

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Which type of reliability refers to measuring reliability by assessing the consistency of observations across raters/judges? 

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Answer

Interrater Reliability

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Which type of reliability tests the consistency of results over time by administering the same test more than once. 

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Answer

Test/Retest Reliability 

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True or False: Alternate-Forms Reliability is when a study splits the test into two parts and measures the stability between measurement items in both test halves. 

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False

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Fill in the blank: A test with ______ validity aims to measure the relevance across all contentitems within the given test, not just in one area. 

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content

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Fill in the blank: Within ___________ research methods, validity and reliability can be determined through the consistency and objectives of the data outcomes, participants, types of tests, and researcher observations. 

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qualitative

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True or False: Construct Validity analyzes the extent to which a test measures the construct it claims to measure. 

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True 

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True or False: By using multiple forms of similar tests, a researcher can indicate whether the measurement is reliable depending on the consistency of an outcome.

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True 

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True or False: Reliability means that a test is measuring what it is supposed to.  

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False

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Fill in the blank: If a test has no or little _______, it will produce results by chance or simply by guessing.  

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validity

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Fill in the blank: A _________ test needs and depends on consistency. 

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reliable

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True or False: When there is a consistent and repeating correlation found in results, the test or tests will be considered reliable in their results.  

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True 

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True or False: A test that has high reliability does not mean that it will have high validity in return. 

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True 

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