confounding bias

Question 1

what is chance and why does is arise

Answer 1

we conduct experiments on pts/observe their samples then use this info to make infeences on the rest of the population

Question 2

what is bias

Answer 2

a systematic error leading to a result which deviates from the truth

ie a flaw in the study design/conduct/analysis which leds ro an incorrect estimate

Question 3

what is selection bias

Answer 3

distortion of the results due to the selection of participants into the study
those in the study do not represent the target population
key to selection bias is that the relationship between exposure and outcome differs for those who participate and those who dont

Question 4

how we minimise selection bias in a case controlled study

Answer 4

at the design stage by drawing cases and controls from the same population

Question 5

how can we minimise selection bias in cohort studies

Answer 5

ensure pt follow up is complete
non differential according to exposure or outcome status

Question 6

what is information bias

Answer 6

distortion of results due to errors in measurement or classification of exposures/outcomes

Question 7

how can we minimise information bias

Answer 7

minimise period of recall where possible
objective measurement of exposures

Question 8

what is confounding bias

Answer 8

bias due to exposure and outcome sharing in a common cause
commonly considered separately to bias but is still a form of bias as it leads to a systematic deviation from the truth
an intuitive concept