JMU merrell final hth 450 FORMULAS

cross sectional: disease prevalence formula

a/a+b vs. c/c+d horizontally across the boxes

cross sectional: exposure prevalence formula

a/a+c vs. b/b+d vertically across boxes

odds ratio formula

cross products: (a x d) / (b x c)

SMR (part of indirect adjustment)

observed deaths/expected deaths after that, multiply again by observed deaths to get the final answer for that pop. write as "__ per 1000"

direct rate adjustment

1. divide deaths/mid yr pop for BOTH POPULATIONS 2. take that number and multiply it by all mid yr pops in reference population (doesn't matter what numbers you use as long as you use the same reference for BOTH pops) 3. add up all expected deaths, get the total for both pops 4. do this for both: (TOTAL EXPECTED DEATHS/TOTAL REFERENCE POP) x 1000 5. write as " __ per 1000" 6. compare the two groups

attributable risk PERCENT

(Incidence in exposed - incidence in unexposed) / incidence in exposed

PAR percent (PAR%)

(incidence in TOTAL POP - incidence in unexposed group)/incidence in TOTAL POP

indirect rate adjustment

1. fill in column with given mortality rates (ex: 4 per 1000 = 0.004) 2. multiply pop values by these rates for each group 3. fill in expected values in expected column 4. SMR: (observed deaths/expected deaths) 5. multiply that number by the observed deaths (tip: observed deaths is usually given to you at the top of the problem near the given mortality rates) 6. write that number as "__ per 1000" 7. repeat for both pops a and b 7. compare rates

case-control looks at ______

disease vs no disease

cohort looks at ____

exposed vs not exposed

PAR (population attributable risk)

incidence in TOTAL POP - incidence in unexposed

attributable risk formula

incidence in exposed - incidence in unexposed

relative risk formula

incidence in exposed/incidence in unexposed (a/a+b) / (c/c+d) or just do the prevalence of disease cross sectional formula and divide them