Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/6

Click to flip

6 Cards in this Set

  • Front
  • Back
5 common sources of bias in a case-control study
1) Failure to randomly sample from the study base (Selection bias). 2) Incomplete disease ascertainment (selection bias). 3) Exposure misclass (differential information bias) 4) Confounder misclass (differential information bias) 5)Chance (inadequate power)
Failure to randomly sample study base
control group has artificially higher or lower prevalence of exposure. Eg. Estrogens and MI: if use trauma controls it will include women with osteoporotic fractures (Estrogens could be low).
Disease ascertainment
Cases and controls recruited separately - selection related to the exposure. To overcome identify all cases within a catchment
Exposure
Exposure is measured after disease. Source of information bias for cases
Confounding
measured after disease
Chance
need massive numbers for good power but usually not a major problem