Epi test

• proportion of peopke w/the disease who have a positive test for the disease
• Sensitivity = a/(a+c)
• (TP / (TP + FN)

• proportion of people withou the disease who have a negative test
• Specificity = d/(b+d)
• (TN / (TN + FP))

• Positive Predictive Value = a/(a+b)
• (TP / (TP + FP))

• NPV = d/(c+d)
• (TN/ (TN + FN)

• any trend in the collection, analysis, interpretation, publication or review of data that canlead to conclusions that are systematically different from the truth
• Selection bias – comparisons between groups that differ in ways other than the mainfactors being studied
• Measurement – measurement different between the 2 groups
• Confounding bias – if factor associated with actual cause-
• Bias can often be prevented by proper study design and corrected through analysisbut the role of chance can only be reduced not eliminated by these measures

the degree to which the results of a study are correct for the sample of patients being studied

the degree to which results of an observation hold true in other settings

occurence of a group of cases in a circumscribed place and time (anecdotal evidence)

occurence of a disease at a rate greater than expected

worlwide epidemic; epidemic crossing continental borders

habitual presence of a disease within a given geographical area

mechanism by which an infectious agrent is spread from a source or reeservoir to another person

common source outbreak where the exposre ocurs in less than one incubation period

common source outbreak where the exposure occurs over multiple incubation periods

transmission occurs from person to person

the study of the distribution and determinants of healh related states or events in specified human populatios and its application to the control of health problems

help us understad the role of chance

understand and describe the epidemiological triad and concepts of person, place, and time; no interventions provided; assessment of potential causes

• aka population or correlation studies
• compare disease rates b/w populations
• exposure is only known for groups, not individuals in the groups

number of NEW cases of disease that occur during specified period of time in a population at risk

incidence when all individuals are at risk for the entire period of time studied

dfft individuals observed for different lengths of time; denominator is the sum of the lengths of time (often expressed as person-years)

the mortality rate in a population for all causes of death during a given time period

the number of deaths from a specified cause per 100,000 person-years at risk

death rate from a specific disease among individuals during a specified period of time (ie. proportion of patients who die of a disease)

incidence of disease among a population at risk observed for a limited period of time, often due to a very specific exposure

number of live births in a population over a given period, usually a year

live births in a population with the denominator restricted to the number of women of childbearing age over a given period