Types of Validity

There are many types of validity and knowing then is extraordinarily useful for achieving the highest possible marks in your OCR A2 Psychology exam.

Validity

Firstly, what is validity?

Validity refers to the extent to which findings or conclusions of a study are actually measuring what they claim to be measuring.

For example: suppose we want to measure the length of a table. So we get a tape measure and then proceed to measure the height of the table legs.

What’s wrong?

Well, we didn’t measure the length of the table. We measured the height of the table instead. So, our measurement of the length of the table is invalid. However, if we had intended to measure the height of the table, then our measurement would be valid, because we have measured the height of the table.

Internal Validity

Internal validity is the measure of the experimenter’s measurement of the dependent variable.

For example: suppose an experimenter wants to measure the reaction times of a person and to measure this they use a person with a stopwatch.

Can you see an problem with this measurement?

The problem is that the person with the stopwatch has to also react. So, we would expect that this measurement is invalid.

A better way to measure this dependent variable would be to use a video camera. This way the experimenter does not have to rely on another person’s reaction times to measure the dependent variable. Thus, making it more valid.

External Validity

External validity is split into two types. Ecological validity and population validity.

External validity refers to the extent to which the findings of a study can generalised. It is important to have high levels of external validity because this directly affects the usefulness of the results and conclusions of the study.

Ecological Validity

Ecological validity refers to the extent to which the results and conclusions are generalisable to real life.

Ecological validity is mainly affected by the task which the participants have to do. Many people say that it is the methodology, for example, laboratory experiments, which affects the ecological validity, but this is not necessarily true. It is possible to have a laboratory experiment which is high in ecological validity because the task that the participants have to do is true to real life.

Let’s look at an example. Imagine that you are an experimenter and you are studying the psychology of shopping interactions with store clerks.

You choose to use a laboratory experiment because it gives you better control over extraneous variables.

You set up a fake shop, which is exactly the same as in real life. You then have you participants go into the store and buy some items that they would normally buy. This, although a laboratory experiment, is high in ecological validity, because the task which the participants have to complete is true to real life.

Population Validity

Population validity refers to the extent to which the sample can be generalised to similar and wider populations.

This type of validity is important because without it the research becomes low in usefulness.

Let’s look at an example.

Suppose we are studying the impact of listening to Mozart on IQ (the mozart effect).

So we decide that we are going to use a sample of people with high IQs and we use a random sample. This sample would have high population validity for people with high IQs, but mainly because we have used a random sample. However this sample would have low population validity for everyone else, because the sample is extremely limited.

Temporal Validity

Temporal validity refers to the extent to which the findings and conclusions of study are valid when we consider the differences and progressions that come with time.

Studies that are temporally valid will either be recent studies or will be studies that consider something which has not changed since the study was completed, for example a study from 50 years ago into people’s perceptions about height may be high in temporal validity because society has not changed its views towards height. However, a study into television advertising in the seventies and eighties may not be temporally valid today because of the many television channels available nowadays compared with the few channels that were available back then. (Take a look at this study for an example that can be considered low in temporal validity: Cowpe 1989)

Face Validity

Face validity refers to the extent to which a study appears to measure what it claims to measure.

This is the type of validity that you should refer to the least because it is not a very good evaluation point, internal validity would be a better type of validity to use. Face validity can be useful to you, because you can easily use it as an evaluation point in your OCR A2 psychology exam if you go blank and can’t think of another evaluation point.

A study with high face validity may look like it is measuring what the researcher is intending to measure, but it does not necessarily mean that the study is measuring what it claims to.

Let’s look at an example.

Suppose we are trying to measure the effects of watching a scary movie on participant stress levels.

We show our participants a scary movie and measure their cortisol levels before and after.

Cortisol is produced in response to stress, which means that on the surface, this study appears as though it is measuring the effects of a scary movie on participant stress level. Therefore it has high face validity.

However, we did not consider the impact of participants not eating when they were watching the film.

We realise that not eating lowered our participants blood glucose levels, which also causes cortisol to be produced. This means that our study, although high in face validity was low in internal validity.

Test Validity

Test validity is composed of several constituent parts.

Test validity refers to the extent to which the results of a study or test can be said to have meaning.

Let’s look at an example.

Suppose we are measuring the intelligence of people. We might use an IQ test. We could argue than an IQ test has a high level of test validity because we can see that it is a well-established test.

Construct Validity

Construct validity refers to the extent to which a study or test measures the concept which it claims to.

There are two types of construct validity: convergent validity and discriminate validity.

Let’s look at an example.

Suppose we are looking into Becker’s (1978) ‘The Health Belief Model’

We find that there are several cognitive heuristics that people employ when they are considering adopting a health behaviour. All of them are present in the health belief model. Therefore we can argue that our study is high in construct validity.

Convergent Validity

Convergent validity refers to the extent to which the constructs that are tested relate with each other.

Discriminate Validity

Discriminate validity refers to the extent to which the constructs tested which don’t have a relationship do indeed not have a relationship with one another.

Content Validity

Content validity follows nicely on from construct validity, as content validity refers to the extent to which a study or test measures up against all the elements of a construct.

For example, let’s suppose we are looking at the effects of stress on worker productivity.

We have our participants answer questionnaires how much they think they are affected by stress in the workplace and how much it affects their productivity.

We could argue that this is low in content validity because it hasn’t actually tested the effects of stress on worker productivity.

Criterion Validity

Criterion validity refers to the extent to which the results and conclusions are valid compared with other measures.

Criterion validity is split into two types of validity: predictive validity and concurrent validity.

Predictive Validity

Predictive Validity refers to the extent to which the results and conclusions can be used to predict real life applications of the study.

Let’s look at an example.

Suppose we are looking into the effects of thinking you are being watched on behaviour.

Our study is a replication of several or other studies that have been previously conducted.

We give our participants a task to complete. During the task they will run into several signs which suggest that they are being monitored, for example, ‘you are being monitored by CCTV operators.’

This study may have predictive validity for similar situations.

Typically predictive validity is established through repeated results over time.

Concurrent Validity

Concurrent validity refers to the extent to which the results and conclusions concur with other studies and evidence.

Let’s look at an example.

Milgram (1963) studied the effects of obedience to authority. Milgram’s results concurred with many replications of the study. Therefore Milgram’s study was high in concurrent validity.

Statistical Conclusion Validity

Statistical conclusion validity refers to the extent to which we can the results are statistically significant, that is, we can establish cause and effect above chance.

Typically in psychological studies chance is established at 5% or >0.05 of chance. This means that if the results are above 5% then we will accept our alternative hypothesis and reject our null hypothesis. This suggests cause and effect between the variables. If the results are below 5% then we will accept our null hypothesis. Having result below 5% of chance means we cannot establish cause and effect because the results have occurred by chance.

Representation Validity

Representation validity, which is also know as translational validity, refers to the extent to which the construct or concept being studied can be translated to real life.

Diagnostic Validity

Diagnostic validity is not used much in the OCR A2 psychology specification. It is most commonly used in clinical settings. Diagnostic validity refers to the extent to which a diagnosis made about a condition is accurate.

Instrumental Validity

Instrumental validity refers to the extent to which the instruments used to measure the dependent variables are correct for that measurement.

For example, referring back to our table study earlier. Suppose now we correctly measure the length of the table, but then we realise that our tape measure is inaccurate. Therefore our study was low in instrumental validity.

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Types of Validity