The Hawthorne effect refers to people’s tendency to behave differently when they become aware that they are being observed. As a result, what is observed may not represent “normal” behavior, threatening the internal and external validity of your research.
The Hawthorne effect is also known as the observer effect and is closely linked with observer bias.
Like other types of research bias, the Hawthorne effect often occurs in observational and experimental study designs in fields like medicine, organizational psychology, and education.
Confirmation bias is the tendency to seek out and prefer information that supports our preexisting beliefs. As a result, we tend to ignore any information that contradicts those beliefs.
Confirmation bias is often unintentional but can still lead to poor decision-making in (psychology) research and in legal or real-life contexts.
Inclusion and exclusion criteria determine which members of the target population can or can’t participate in a research study. Collectively, they’re known as eligibility criteria, and establishing them is critical when seeking study participants for clinical trials.
This allows researchers to study the needs of a relatively homogeneous group (e.g., people with liver disease) with precision. Examples of common inclusion and exclusion criteria are:
Study-specific variables: Type and stage of disease, previous treatment history, presence of chronic conditions, ability to attend follow-up study appointments, technological requirements (e.g., internet access)
Predictive validity refers to the ability of a test or other measurement to predict a future outcome. Here, an outcome can be a behavior, performance, or even disease that occurs at some point in the future.
Predictive validity is a subtype of criterion validity. It is often used in education, psychology, and employee selection.
Concurrent validity shows you the extent of the agreement between two measures or assessments taken at the same time. It compares a new assessment with one that has already been tested and proven to be valid.
Concurrent validity is a subtype of criterion validity. It is called “concurrent” because the scores of the new test and the criterion variables are obtained at the same time.
Establishing concurrent validity is particularly important when a new measure is created that claims to be better in some way than existing measures: more objective, faster, cheaper, etc.
Ecological validity measures how generalizable experimental findings are to the real world, such as situations or settings typical of everyday life. It is a subtype of external validity.
If a test has high ecological validity, it can be generalized to other real-life situations, while tests with low ecological validity cannot.
Ecological validity is often applied in experimental studies of human behavior and cognition, such as in psychology and related fields.
Criterion validity (or criterion-related validity) evaluates how accurately a test measures the outcome it was designed to measure. An outcome can be a disease, behavior, or performance. Concurrent validity measures tests and criterion variables in the present, while predictive validity measures those in the future.
To establish criterion validity, you need to compare your test results to criterion variables. Criterion variables are often referred to as a “gold standard” measurement. They comprise other tests that are widely accepted as valid measures of a construct.
The researcher can then compare the college entry exam scores of 100 students to their GPA after one semester in college. If the scores of the two tests are close, then the college entry exam has criterion validity.
When your test agrees with the criterion variable, it has high criterion validity. However, criterion variables can be difficult to find.
Discriminant validity refers to the extent to which a test is not related to other tests that measure different constructs. Here, a construct is a behavior, attitude, or concept, particularly one that is not directly observable.
The expectation is that two tests that reflect different constructs should not be highly related to each other. If they are, then you cannot say with certainty that they are not measuring the same construct. Thus, discriminant validity is an indication of the extent of the difference between constructs.
Discriminant validity is assessed in combination with convergent validity. In some fields, discriminant validity is also known as divergent validity.
Convergent validity refers to how closely a test is related to other tests that measure the same (or similar) constructs. Here, a construct is a behavior, attitude, or concept, particularly one that is not directly observable.
Ideally, two tests measuring the same construct, such as stress, should have a moderate to high correlation. High correlation is evidence of convergent validity, which, in turn, is an indication of construct validity.
Content validity evaluates how well an instrument (like a test) covers all relevant parts of the construct it aims to measure. Here, a construct is a theoretical concept, theme, or idea: in particular, one that cannot usually be measured directly.
Content validity is one of the four types of measurement validity. The other three are:
Face validity: Does the content of the test appear to be suitable for its aims?
Criterion validity: Do the results accurately measure the concrete outcome they are designed to measure?
Construct validity: Does the test measure the concept that it’s intended to measure?