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Thursday, September 16, 2021

validity

What is validity?

validity

n  The word "valid" is derived from the Latin validus, meaning “strong”.

n  Validity is the extent to which a concept, conclusion or measurement is well-founded and corresponds accurately to the real world.

n   “Validity is the extent to which a test measures what it claims to measure”

               In valid               Valid

n  What is Test validity?

  the extent to which inferences, conclusions, and          decisions made on the basis of test scores are

appropriate and meaningful.”

n   is considered to be the degree to which the tool measures what it claims to measure.

n  e.g a test of reading comprehension should not require mathematical ability.

What is Importance of Validit?

n  Educational assessment should always have a clear purpose.

n  Nothing will be gained from assessment unless the assessment has some validity for the purpose.

n  The validity of a test is critical because, without sufficient validity, test scores have no meaning.

n  It is vital for a test to be valid in order for the results to be accurately applied and interpreted.”

n  Validity is important because it can help determine what types of tests to use,

n  For that reason, validity is the most important single attribute of a good test.


v   What is  Construct validit?

v   

n  The overall validity of a measurement method is sometimes referred to as its construct validity.

Ø  It refers to a measure of the extent to which a test measures a hypothetical and unobservable variable or quality

Ø  refers to the extent to which operationalization of a construct  do actually measure what the theory says they do. It also refers to the extent to which operationalization of a construct  do actually measure what the theory says they do.

 For example:

Ø   To what extent is an IQ questionnaire actually measuring "intelligence"?

Ø  Does a self-esteem scale really measure self-esteem?

 

v  Convergent validity :

           refers to the degree to which a measure is correlated with other measures that it is theoretically predicted to correlate with.

v  Discriminant validity :

v         tests whether concepts or measurements that are supposed to be unrelated are, in fact, unrelated  Discriminant validity=

n  is the extent to which people’s scores are not correlated with other variables that reflect distinct constructs.

n  example, that a researcher with a new measure of self-esteem claims that self-esteem is independent of mood

n  Then this researcher should be able to show that his self-esteem measure is not correlated with a valid measure of mood.

n  is a non-statistical type of validity

n   that involves "the systematic examination of the

n  test content to determine whether it covers a representative sample of the behavior domain to be measured" (Anastasi & Urbina, 1997 p. 114).

n  e.g. does an IQ questionnaire have items covering all areas of intelligence discussed in the scientific literature?

n  A course exam has good content validity if it covers all the material that students are supposed to learn

 


Things to remember about:

 content validity

 The evidence of the content validity of your test is found in the Table of Specification.

This is the most important type of validity to you, as a classroom  teacher.

There is no coefficient for content validity. It is determined judgmentally, not empirically.

Types of Content validity

      Representation validity:

Ø       also known as translation validity,

 is about the extent to which an abstract theoretical construct can be turned into a specific practical test

v  Face Validity:

                   It is the extent to which the measurement method appears “on its face” to measure the construct of interest.

n  is an estimate of whether a test appears to measure a certain criterion; Unlike content validity, face validity is not investigated through formal procedures

n  It is not determined by subject matter experts.

n  Instead, anyone who looks over the test, (including examinees and other stakeholders) may develop an informal opinion

n  People might have negative reactions to an intelligence test that did not appear to them to be measuring their intelligence.

n  For instance:

n         Does the Rosenberg Self-Esteem scale   appear to be measuring self-esteem?  

n   As to whether or not the test is measuring what it is supposed to measure.

Criterion validity

Ø  It is the extent to which people’s scores are correlated with other variables or criteria that reflect the same construct.

Ø  it compares the test with other measures or outcomes (the criteria) already held to be valid.

v  Example:

Ø   An IQ test should correlate positively with school performance. 

Ø  An occupational aptitude test should correlate positively with work performance.

Ø  Types of CRITERIAN VALIDITY

Ø  Concurrent validity

Ø  refers to the degree to which the operationalization correlates with other measures of the same construct that are measured at the same time.

Ø  Predictive validity

Ø   refers to the degree to which the operationalization can predict (or correlate with) other measures of the same construct that are measured at some time in the future

Ø  Predictive validity

Ø       refers to a measure of the extent to which a person’s current test results can be used to  estimate accurately what that person’s performance or other criterion,

Ø  This type of validity is especially useful for test purposes such as selection or admissions.

Ø  e.g.as test scores will be at the later time

Experimental validity

Ø  The validity of the design of experimental research studies is a fundamental part of the scientific method,

Ø  a concern of research ethics.

Ø  Without a valid design, valid scientific conclusions cannot be drawn.

Types of Experimental validity

n  Statistical conclusion validity

          is the degree to which conclusions about the relationship among variables based on the data are correct or ‘reasonable’.

Ø  It involves ensuring the use of adequate sampling procedures, appropriate statistical tests, and reliable measurement procedures.

Ø  Types of Experimental validity

n  Internal validity

Ø  is an inductive estimate of the degree to which conclusions about causal relationships can be made

Ø   (e.g. cause and effect)

Ø  based on the measures used, the research setting, and the whole research design.

Ø  External validity

Ø  concerns the extent to which the (internally valid) results of a study can be held to be true for other cases

Ø  (different groups of people, settings, different conditions, etc.)

e.g. If the same research study was conducted in those other cases, would it get the same results?

Types of external validity

Ecological validity

Ø  Ecology :

Ø  the science of interaction between organism and its environment

Ø  is the extent to which research results can be applied to real life situations outside of research settings.

Ø  To be ecologically valid, the methods, materials and setting of a study must approximate the real-life situation that is under investigation

 Diagnostic validity:

               In clinical fields such as medicine,

Ø  the validity of a diagnosis, and associated diagnostic tests or screening tests, is extremely important.

Ø  it is essential to know that when running diagnostic tests that clinicians are truly testing what they intend to test.

Ø  An important requirement in clinical diagnosis and testing is sensitivity and specificity

Ø  A test needs to be sensitive enough to detect the relevant problem if it is present

Ø  But specific enough not to respond to other things

In psychiatry there is a particular issue with assessing the validity of the diagnostic categories themselves. In this context:

Ø  content validity may refer to symptoms and diagnostic criteria;

Ø  concurrent validity may be defined by various correlates or markers, and pserhaps also treatment response;

Ø  predictive validity may refer mainly to diagnostic stability over time;

Ø  discriminant validity may involve delimitation from other disorders.

n  Measurement of Validity:

n  There are some extremely important points to remember about the way that psychologists evaluate the validity of a measurement method.

  • First, this process requires empirical evidence.

Ø   A measurement method cannot be declared valid or invalid before it has ever been used and the resulting scores have been thoroughly analyzed.

Ø  Second, it is an ongoing process.

Ø  The conclusion that a measurement method is valid generally depends on the results of many studies done over a period of years.

Ø  Third, validity is not an all-or-none property of a measurement method.

Ø  It is possible for a measurement method to judged "somewhat valid" or for one measure to be considered "more valid" than another. E.g.  an English-language achievement test is valid for children who are native English speakers but not for children who are still in the process of learning English. “The volume of your voice does not increase the validity of your argument.”

Ø  Steve Maraboli 

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