Chapter 7 Describing Health Conditions: Understanding and Using Rates Flashcards
what is the most basic measurement
frequency
how to get a ratio
dividing one quanity by another
proportion is a type of
ratio
what is the difference between a ratio and proportion
proportion includes the quantity in the numerator as a part of the denominator
what does proportion demonstrate
relationship of a part to a whole
rate defitnion
primary measurement used to describe the occurrence of a state of health in a specific group of people in a given time peroid
rates are the best indicator of
the risk (probability) that a specific disease, condition, or event will occur
why do we use rates rather than counting the cases
rates take into consideration the size of the population at risk and the time frame into account
what can rates indicate
indicidence or prevalence
in a rate everyone included in the denominator should be
at risk for the event in the numerator
rate formula
number of conditions or events within a designated peroid of time
_____________________________________
population at risk during the same period
X multiple of 10
specific rates calculated by person, place, and time provide
the best description of a health condition
crude rate defintion
measurement of the occurrence of the health problem or condition being investigated in the entire population
crude rate can lead to
bias of data
what is bias of data
calculating crude rates may obscure important information
EX: entire population in its denominator, births can occur only to females who are childbearing age
if we have bias of data then what can we do to fix this
statistical procedure that removes the effects of differences in the composition of a population, such as age, when comparing one with another
age adjusted rates are meaningful only as
a comparision
incidence rate
measure of the probability that people without a certain condition will develop that condition over a period of time
indcidence
new
prevalence
new and old
prevalence rate
measures the number of people in a given population who have an existing condition at a given point in time
peroid prevelaence
existence of a condition during a peroid of time
point prevalence
at a specific point in time or may refer to an event that happens to different people at different times
prevalence is influence by two factors
number of people who have developed the condition in the past
duration of illness
prevalence rate formula
number of exisitng cases
___________________________
total population
indcident rate fomula
number of new cases in given time period
_________________________________________
population at risk in same time peroid
what does the denominator of incidence include
those only at risk
things that can impact prevalence
increase in incidence = increase
increase in reoccurrence = increase
increase in cure = decreases
increase in death = decreases
incidence density
use of a person-time denominator int he calucaiton of rates
person day reflects
one person at risk for one day
person year represents
person at risk for 1 year
attributable risk
difference between incidence rates in an exposed group and unexposed group
relative risk ratio
the ratio of the incidence rate in the exposed group and the indicence rate in the non exposed group
PMR does what
compares deaths form a specific illness to deaths from all other causes
incidence density formula
new cases occurring during the study peroid
_______________________________________
person time units accumulated by subjects during the study peroid
attributable risk formula
incidence rate in the exposed - incidence rate in the non exposed
attributable risk formula measures
risk of a condition
1.0 relative risk
risk is equal for both groups
> 1 relative risk
greater risk to the exposed group
(Risk factor 6 = 6 time more likely to develop it)
<1 relative risk
may show protective property against the condition under study
not usually very common
sensitivity
the ability of a test to identify correctly people who have the health problem under study
sensitivity test
positive
specificity
the ability of a test to correctly identify people who do not have a health problem
specificity test
negative
what is the test that is useful for a rare disease
sensitivity
