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.
Fg. 1 Reliability and validity, commons.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:
Trait Error
In trait errors, issues of reliability stem from the actual subjects of the experiments.
Questions asked about trait error include:
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:
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.
Explanations 
Exams 
Magazine 
