Test 5 - epi/biostats

Question 1

Define Lead time bias

Answer 1

Overestimation of survival duration among screen-detected cases (relative to those detected by signs and symptoms) when survival is measured from diagnosis.

Question 2

Define length bias

Answer 2

Overestimation of survival duration among screening-detected cases caused by the relative excess of slowly progressing cases.

Question 3

Define Referral bias

Answer 3

When characteristics of the people that get screened differs from unscreened people.

Question 4

Define Spectrum bias

Answer 4

Study is being conducted with a highly selected group of patients

Question 5

Define verification/work-up bias

Answer 5

Only some patients get the gold standard test (probably the patients who you truly suspect have the disease)

Question 6

Define differential bias

Answer 6

When different reference tests are used for different patients.

Question 7

Define observer bias

Answer 7

Occurs when the test in very subjective or done by a person who knows the subject