Measuring health Flashcards
wk 4
What is the purpose of descriptive studies?
generates a hypothesis but can’t confirm it
what are the three types of descriptive studies?
Case studies, case series and cross-sectional survey
What is the purpose of case study?
Understanding the report of ONE patient (them and the disease) to generate a hypothesis about expsoure and disease relationship
What is the structure of a case study?
Examine one patient aksing questions about life, background, exposure and disease.
what is the purpose of case series?
To describe the common features and generate a hypothesis about exposure.
What is the structure of case series?
Small collection of cases with common characteristics
What is the purpose of cross sectional studies?
assess the status of the disease or a population at the same point in time.
Can’t show case and effect as snapshot at the same time.
What is an example of a cross sectional study?
5000 Aus Post employees asked about their weight and PA at the same time.
What are observational studies?
researcher does not alter what occurs
What is the result of observational studies?
reflects what happens in real life but is subject to bias
what are interventional studies?
research changes something and then obsevres the result. Exposure and then watch ouctome
What is the result of interventional study?
less bias but is less refelctive of real life.
What is the purpose of analytical studies?
attempts to qualify relationship between factors
what are the types of analytical studies?
Case Cohort, case control and randomised controlled trail
What type of study is RCT part of?
Prospective cohort
Is the disease present in case-control studies?
yes - have disease first and then try to find exposure
Is the disease present in cohort studies?
no- have exposure and then try to determine what the disease will be
What is the outcome and study factor of case-control studies
O= expsore SF= Disease
What is the outcome and the study factors of cohort studies?
O= disease SF= exposure
What is an example of a case-control study?
1952 study of 700 M and W with lung cancer and 700 without. looked at smoking history and other information.
What are case-control study always?
retrospective (looks back)
What type of study is a case-control?
analyical - observational
What type of study is a RCT?
analytical - INTERVENTIONAL (only one)
What are the two groups in a randomised control study?
Control group and study group
How are the groups assigned in RTC?
Randomly
What is the control group also known as?
Comparison group
What must the comparison group be made up of and why?
People that are as alike to the study group as possible. otherwise is confounding.
What is an example of Cohort study?
Workers at factory are exposed to asbestos fibres- ask: does exposure to asbestos cause mesothelia?
What is confounding?
Third variable is actually the reason for both the disease and the exposure. Thir varible not in postulated pathway.
What does the Compounding variable need to be for it to actually be compounding?
independently associated with BOTH presumed exposure and outcome
What are compounding factors?
age, height, upbringing, origin, background, gender etc.
What are the three types of bias?
Confounding, selection and information
what is selection bias?
when the way that people have been selected disorts estimation because there is a difference between participants and non participants or those getting control and those not.
What is information bias?
information collected differently between two study groups.
What are four ways that researchers make a control group that avoids bias?
restriction, matching, randomisation and statistical methods.
How does restriction work?
only have people in certain category (age, gender or ethnicity etc)
How does matching work?
Match a person in study group to the person in control group
What is the effect of randomisation?
Equally distributes the potentially compounding factors removing chance of bias and that it is reflective of the study group.
What is single blinding?
Participant OR researcher DON’T know which arm in.
What is double blinding?
BOTH participants and investigator unaware of who getting what.
What is incidence?
Number of NEW cases that arise in a given period of time.
What is Prevalence?
Number of existing cases in a given time period.
What is the importance of calmative incidence?
understanding the probability/risk that individual will develop something over time.
How is incidence calculated?
no of new cases in period / number of people at risk
How is prevalence calculated?
total number of cases / total population
What is the main purpose of incidence and prevalence?
They both give society measures of disease frequency.
If the incidence is LOW but duration is LONG =
prevalence is HIGHER than incidence
if incidence is HIGH and duration is short =
prevalence is LOWER than incidence
Why do we use age-standardisation?
Age can be a confounding factor so need to make specific rates
Generally, how is age standardisation made?
Age- standardisation measurement AGAINST a standard reference of population
What is CDR?
Crude Death rate and calculates total number of deaths per 1000
How is CDR calculated?
Total population deaths/ total population
What are the steps for calculating Age Specific death rates?
Amount of deaths in age range/ total population in that age range
then; put in rate per 100 000
What is the effect of age-standardisation?
Allows two populations to be compared on a standard level without compouding bias.
