CE

Question 1

Name the types of variables

Answer 1

Numerical

Categorical

Question 2

Can a variable be both a numerical and a categorical?

Answer 2

Yes numerical values can be put into categories, however categorical values cannot be changed to numerical value

Question 3

Name the variable 2 types of numerical variables

Answer 3

Continuous variable

Discrete variable

Question 4

Which variable is presented in a frequency table

Answer 4

Categorical variable

Question 5

Name the 2 types or Categorical vaiables

Answer 5

Ordered categorical

Unordered categorical

Question 6

What is a binary/ dichotomous variable

Answer 6

This is a type of unordered categorical variable that only has 2 groups.

Question 7

When do we use a histogram rather than a bar chart?

Answer 7

When the variable is numerical

Bar charts and frequency tables are used for categorical data

Question 8

What is another term for RISK?

Answer 8

Cumulative incidence

Question 9

What is the difference between risk and prevalence

Answer 9

Prevelance shows the amount of disease at a particular time whereas the risk talks about the number of new cases over a period of time

Question 10

What is the equation for 95% reference range?

Answer 10

mean +/- ( 1.96 X Standard Deviation)

Question 11

What is an interventional study

Answer 11

This is where the investigator assesses whether changing/ modifying something affects the progression of a patients disease.

Question 12

Name 3 observational studies

Answer 12

Case-control
Cohort study
ecological
descriptive
cross sectional

Question 13

Define accuracy

Answer 13

Relates to how representativethe sample is to the true population

Question 14

Define Precision

Answer 14

Relates to the amount of variation between the sample

Question 15

Name the types of bias (internal validity)

Answer 15

Selection bias

Measurement bias

Question 16

Define Standard deviation

Answer 16

A measure of the

spread of observations around the mean

Question 17

Define standard error

Answer 17

Measures the precision of the sample mean as an estimate of the populaton mean

Question 18

What is the equation for SEM?

Answer 18

SEM= SD / √N

Question 19

What is the equation for 95% Confidence interval?

Answer 19

CI = (statistic) +/- (1.96 x SE)

Question 20

When do you use a Reference range and not a Confidence interval

Answer 20

RR measures the variation between individual observations in the sample, whereas CI shows the variation in a group of individuals

Question 21

List the 3 criteria for a variable to be a confounder?

Answer 21

1. Associated with the exposure
2. Be a risk factor for the disease
3. Must not be on the causal pathway between disease and exposure

Question 22

On what occasion would the Risk ratio and Odds ratio be similar

Answer 22

When the disease is rare

Question 23

Define case-control study

Answer 23

When individuals are recruited on the basis of their outcome/ disease and then their past exposure is investigated AND a control group is picked with similar properties but no disease

Question 24

Name the types of cohort studies

Answer 24

Historical

Prospective

Question 25

What is a prospective cohort study?

Answer 25

When a sample of people with a certain criteria are picked and then followed up over a couple of years to see if the outcome develops.

Question 26

What is a historical cohort study?

Answer 26

Subjects who already have the outcome are selected and researchers try and investigate their past exposure. (No control group with no disease)

Question 27

How can a variable be classed as a confounder?

Answer 27

1. Associated with the exposure
2. Risk factor for the disease
3. Must not be on the causal pathway between Exposure and disease

Question 28

How to remove confounders?

Answer 28

1. Randomisation-

2. Exclusion: use subjects from the same criteria- e.g same social class

Question 29

What is a Multivariable model?

Answer 29

It’s a model that takes into account the effects of many different confounders

Question 30

Name the models that combine association estimates after stratification.

Answer 30

1. Mantel-haenszel methods

2. Regression models

Question 31

What are correlation and linear regression used for?

Answer 31

Models that are used to investigate the association between two numerical variables

Question 32

What is the regression line?

Answer 32

The line/equation which best describes the relationship between 2 variables.