W3 Measurement, Reliability, Validity Flashcards
Measurement
if a thing exist it exits in some amount, and if exists in some amount, it can be measured
A research question
Exposure Measurement
Available dose:
Administrated dose:
Absorbed dose (uptake):
Active dose (biologically effective):
Available dose: cumulative vs current
Administrated dose: the amount that comes in contact
Absorbed dose (uptake): the amount that enters the body
Active dose (biologically effective): that actually affects the specific target organ
-can be substituted for each other if the mechanism is known
Count
-the number of occurrence of an event
ex,
- in a major Canadian city, average annual number of homicides (30 homicides/ year in the 1970’s, 50/year in the 1990’s, 90/year in 2020-21)
-45 individuals older than 75 admitted to a hospital in London for hip fracture
Ratio
-relationship between 2 numbers
-Numerator NOT in the denominator
ex, (binary) sex ratio
Proportion
-relationships between 2 numbers
-numerator necessarily INCLUDED in the denominator
-proportion always range between 0 and 1
Odd
the probability of an event occurring relative to to it not occuring
Rate
speed of occurrence of an event over TIME
Numerator
-# of EVENTS observed for a given time
Denominator
-population in which the events occur (POP AT RISK)
-incorporates a set period of TIME
Measure of Health Events
Measures of Prevalence
What is Prevalence Rate?
What studies is this obtainable from?
What are the two types of prevalence
Prevalence rate: the proportion of the population (or the population sample or the sample subset that has a given disease or other attribute at a specified period of time
Obtained from cross-sectional studies
Two types:
Point prevalence rate and period prevalence rate
Point PR:
PPR= # with disease at SPECIFIC TIME
___________________________
Population at SAME TIME
Example 2: Prevalence of Arthritis in Postmenopausal Women
Period PR= go over
Period PR= # with disease at specific TIME PERIOD
________________________________
Total defined population at same period
Measures of Incidence
Incidence Rate:
Incidence Rate: the proportion of the Population At Risk that DEVELOPS a given disease or other attribute during a specified time period.
-Obtainable from cohort (longitudinal) studies (session 6, oct 14)
What is the pop at risk?
What is the correct numbe rof peole going to the denominator?
Whom should be excluded?
Relationship between prevalence and incidence
Incidence (develop disease)
-measures frequency of disease ONSET
-WHAT IS NEW
Prevalence(has disease)
-Measures population disease STATUS
-WHAT EXISTS
the next step is death or recovery
-incidence and prevalence may be expressed in any power of 10 (Per 100, 1000, 10,000, 100,000)
-more when we lear designs
Incident rate
Incident rate= # new events during specified time period
__________________________________
Population ‘at risk’
Example #2: IR of depression during 1st year of university
Measures of Association
Four Hallmarks of Health Studies
1) a research question/plausible theory
2) A well thought design to address the research question
3) Measurement of exposure and outcome
4) Analysis to compare groups (i.e, rates of disease among exposed vs in unexposed
4 main focus (refer to image)