Chapter 3

• Frequency claim – claim that describes a particular rate or degree of a single variables
• Association claims – argue one level of the variable is likely to be associated with a particular level of another variable

  • Correlational study – variables are measured + relationship between them is tested
  • Variables co-vary
  • Stronger the relationship = more accurate prediction
• Causal claims – one variable is responsible for changing the other

  • Variables covary
  • One causes the other

  To move from association to causality:

  1.    Causal + outcome variable must be correlated

  2.    Causal variable came first, outcome later

  3.    No other explanations that exist for the relationship
• Validity = appropriateness of a conclusion or decision
• Construct validity = how well conceptual variable is operationalised (how well a study has measured or manipulated a variable)

  • Establish each variable has been measured reliably
  • Different levels of a variable accurately respond to differences
• External validity = how well the results of a study generalise/represent people/contexts beyond the original study
• Statistical validity = extend statistical conclusions are precise, reasonable + replicable

  • Point estimate = single estimate of some population value
  • Precision – confidence intervals = given range indicated by a lower and upper value that captures the population value for some point estimate
  • Improves with multiple estimates
• Internal validity = in a relationship between one variable (A) and another (B) – the extent to which A rather than another variable (C) is responsible for changes in B
• Frequency claims  - construct, external + statistical