Ress exam Flashcards
What is the epidemological triad?
Place, time person
What does incidence meam?
The number of new cases in a given time
What is the incidence rate?
The number of people who get a the diseaes in pre defined time/ the number of people at risk (who can get the disease)
What is prevelance?
The number of people who a disease amongst a population at a specific time.
what is the effect of short duration and long duration illness on prevelance and incident?
Short duration illness will have a high incident but a short prevelance
Long duration illness will have a low incident but a high prevelance
Prevelance good for chronic disease
What is case fertality rate?
The number of people who die from a disease in a given period/ the number of people with the disease
What is mortality rate?
The number of people wh die due a diseae in a period/ the number of people who die in a period
what is the aim of “adjustment”?
To reduce the effect of a factor that may swerve the results.
For example adjustment to compare people of a high average age in a population and a low average age in a population
How is “adjustment” done?
By statum specific rate e.g. sex and age
What is risk?
The probability of a disease occuring
1–> certain to happen
0–> Will not happen
How do you calculate the risk?
The number of new cases/the number of people at risk
Give a example of risk?
You apply risk to a group not a person as a person is either going to get the disease or is at risk of getting the disease.
For example 1 in 5 people will get lung cancer who smoke for example.
Therefore there is a 0.2 risk of getting lung cancer if you smoke
What is the aim of the risk ratio and in what study will risk ratio be used in?
Risk ratio aims to find out the risk factor (exposure) of the risk–> the relative risk
It is only used in cohort studies
What do the relative risk values mean?
Less than 1, more than 1 and = 1
If the relative risk = 1 then the effect of exposure is same as unexposure
If the relative risk >1 then the exposure associated with harm
If the relative risk is
How do you calculate the relative risk?
The risk for the treated group/the risk of the control group times by 100
What is relative risk reduction?
100- relative risk.
The reduction in risk in the treated group compared to the untreated group
What is odds?
The probabilty that a event does occur/the probablity a event does not occur
What is the difference in use between risk ratio and odds ratio?
Risk ratio only used in cohort studies while odds ratio is used in case/randomised control studies
What studies is odds ratio used in?
Case/randomised control studies
What is dichomotous variable?
When it can only be one of 2 variables?
Dead or alive
DIsease or undisease
what is population?
Every person in a defined group of interest
What is categorical variable?
Results that can be assigned to a single category
For example male female
Black, blue, red
What is the subdivision of Categorical variables and give examples?
Nominal–> Category with no natural ordering. E.g. Male and female. Black, white, yellow etc
Orderinal –>Category with natural ordering. For example the severity of pain. Very bad, bad, okay , good.
What is numerical values?
Ones that take numerical values
What are the two subdivisions of numerical values?
Discrete –> whole numbers e.g.Number of hospital visits 81, 72
Continous–> no restriction on value e.g. Weight can be 81.245kg , 74,34kg
What is frequency?
The rate of somethign happening
What does the frequency table show?
The frequency and relative frequency
What type of data is bar charts appropiate for?
Categorical or discrete numerical data
What type of data is pie chart used for?
Categorical or discrete numerical data
What is the difference between histograms and bar charts?
Each bar in bar chart is seperate
While in histogram it is continous
When histograms used?
For the display of frequency and continous variables
What is the mean?
The average of all the values
What is the median?
The middle value of all the values
What are the different quartile ranges?
Q1: lower quartile is the median of the lower values. 25% of the values are below this
Q2: the median. 50% of the value are below this
Q3: Upper quartile, the median of the upper values, 75% of the value are below this.
What is standard deviation?
What do you square root
It is only appropiate for numerical value.
It is the measure of the spread of the values from the mean.
The greater the standard deviation the greater the spread of the values from the mean.
The square root of the variance
What does it mean by outcome and exposure?
Outcome is what you are measuring
While exposure is what affects the outcome
If the outcome is numerical and the exposure is numerical what is the analysis?
Correlation
If the outcome is numerical and the exposure is categorical (independent groups) what is the analysis?
T test or Mann Whitny U test
If the outcome is numerical and the exposure is categorical (non-independent groups) what is the analysis?
Paired T test or Sign test
The groups are related to one another
What is the confidence interval?
Usually at 95% where if the results were done 100 times then 95 times the results will be within that range