STATS lec 9- Validity

Question 1

Validity

Answer 1

• Valid: well grounded in logic or truth
  
  • Gives us a true interpretation

Question 2

Forms of validity 1- Face validity

Answer 2

• Face validity
• Does it measure what it says it does
  
  • Do the questions in a stats exam reflect the knowledge students should have learnt
  • If the outcome wanted is a reduction in heart attacks, is measuring BP a goodway of assessing this?
  • Is the way an answer to a question in a survey is interpreted valid

Question 3

Forms of validity 2- Criterion validity

Answer 3

• Criterion validity: does the measure give results which are in agreement with other measures of the same thing?
  
  • e.g. do theoretical research methods exam scores relate to practical research scores
  • Concurrent: comparison of the new test with an established test
    
    • new intelligence test vs IQ
  • Predictive: does the test predict the outcome of some future attempt
    
    • STATS vs A-level results

Question 4

2 types of criterion validity

Answer 4

• Concurrent: Comparison of new test with established test
  
  • e.g. new intelligence test c.f. IQ
• Predictive: does the test predict the outcome of some future attempt
  
  • E.g. do your STATS scores predict you A level grades

Question 5

Forms of validity- Construct validity

Answer 5

• Construct validity: How well does the test tap into the underlying construct
  
  • e.g. does a stats exam actually measure status knowledge (or is it testing memory)
  • Is a score of 30 on a personality scale a good measure of personality changes in schizophernia

Question 6

Forms of validity- Ecological validity

Answer 6

• Ecological validity: does the study reflect naturally occuring behaviour
  
  • e.g. would the performance of students in practical labs be equivalent to the performance of those students in a real setting
  • Do students in the dispensary react to a prescription in the same way as they do in “real life”
  • Would an animals behaviour in captivity tell you anything about animals in the wild

Question 7

Forms of validity- population validity

Answer 7

• Population validity: is our sample adequate for the claims we make about the population
  
  • e.g. if we measured attitudes to recreational drug use form a sample in this lecture, could we generalise the results to conclude the attitudes of everyone/young people/ students/ Aston students/ Pharmacy staff
  • Sampling is important

Question 8

Sampling

Answer 8

• VERY important, if you get it wrong you can compromise your population validity
• (And therefore your conclusions may be wrong)
• See lec 8 + 9