Chance, Bias & Confounding

Precision

Validity

Random Error

Statistical Interference: The aim is to draw conclusions about the population based on our sample

Controlling RE

Validity is the degree to which the inferences drawn from the study are warranted.

Increasing Sample Size = Increases Precision

Precision gives as a margin between which we have some confidence our source population parameter sits within, based on our sample estimate

  • Bias will always be there, we need to MINIMISE it as best we can

Internal Validity: This refers to how well the study has been conducted

External Validity: This is the extent to which the results obtained from the sample in the study can be generalised

  • Lack of Precision

-Caused by Chance

  • Sample may not be completely representative of our source population

When the observed value of a sample differs form the true population (due to chance alone)

  • efficient study design that maximises information
  • precise instruments
  • repeating a measuremenT
  • adequate sample size