lay definitions

Question 1

Sensitivity

Answer 1

Proportion of individuals with disease that have positive test result e.g. sensitivity 66% 2:3 of the individuals who have the disease will be identified by testing; 1:3 with disease will be testing negative and missed

Question 2

False negative

Answer 2

Test result is negative in the presence of the disease

Question 3

Specificity

Answer 3

Proportion of individuals without disease that have negative test result

e. g. specificity 90% 9:10 of the individuals who don?t have the disease will test negative;
1: 10 without disease will be incorrectly labelled with disease

Question 4

False positive

Answer 4

Test result is positive in the absence of the disease

Question 5

Positive predictive value

Answer 5

Proportion of individuals with positive test who truly have the disease
e.g. PPV 90% 9:10 of those who tested positive have the disease; 1:10 test positive but don?t have the disease

Question 6

Confounder

Answer 6

A factor (exposure) which can explain (entirely or partially) the observed association between ?exposure? and ?outcome?

A confounder is a factor that distorts the association between ?exposure? and ?outcome?

Question 7

Interaction

Answer 7

The association between ?exposure? and ?outcome? is of different strength in different strata of another factor e.g. the association between smoking and lung cancer is stronger in older people than in younger people. In this association, age is the effect modifier

Question 8

Crude estimate

Answer 8

Estimate derived without accounting for the effect of confounders (such as age, sex)

Question 9

Adjusted

estimate

Answer 9

Controlled for the effect of confounders

Taking into account ?factors? (such as age, sex, deprivation, etc) that distort the association between ?exposure? and ?outcome?

Question 10

Regression analysis

Answer 10

Statistical method that accounts simultaneously for multiple confounding factors

Question 11

Standardisation

Answer 11

A way of controlling for age (or other potential confounders) so that rates of disease or death in populations with different age structures (or other potential confounding factors) can be compared

Question 12

DSR

Answer 12

A method used to account for the difference in the age structure (or in other confounders) of populations in order to make a valid comparison of rates of disease/death

Question 13

SMR

Answer 13

A method used to account for the difference in the age structure (or in other confounders) of populations in order to make valid comparison of death rates

Question 14

p-value

Answer 14

The probability of having the observed estimate due to chance e.g. if P < 0.05 the difference observed occurs by chance alone less than 5 times in 100

Question 15

95% Confidence interval

Answer 15

95% confident that the true effect size lies within this range, uncertainty range

Question 16

Power

Answer 16

Indicates how good a study is in identifying an effect (or difference in intervention) if in reality an effect (or difference) exists

Question 17

Precision

Answer 17

Refers to the width of the

confidence interval

Question 18

Prevalence

Answer 18

Proportion of existing cases

Question 19

Incidence risk

Answer 19

Proportion of new cases developed during a given time

Question 20

Incidence rate

Answer 20

Number of new cases over the sum of the different times each individual was at risk

Question 21

Risk

Answer 21

Probability that an event will occur

Question 22

Odds

Answer 22

Probability that an event will occur

Question 23

Rate

Answer 23

Measure of effect (e.g. death) changing with time

Question 24

Hazard

Answer 24

Rate

Question 25

Risk ratio

Answer 25

Probability of having the outcome among exposed as compared to ?unexposed?

Question 26

Odds ratio

Answer 26

e.g. OR of lung cancer with smoking of 1.3

30% increase in the likelihood of developing lung cancer among smokers as compared to non-smokers

Question 27

Attributable fraction

Answer 27

Proportion of cases that would be avoided if the exposure is removed

Question 28

Population
attributable
fraction

Answer 28

How much of the disease burden could be prevented by eliminating exposure

Question 29

NNT

Answer 29

Number of patients that need to receive an intervention over a certain period to prevent one outcome

Question 30

Mean

Answer 30

Average

Question 31

Mode

Answer 31

Most common observation

Question 32

Median

Answer 32

Middle observation

Question 33

Quintiles /

Deciles

Answer 33

Data broken down into 5 / 10 sections, each having 20% / 10% of the values. e.g. first quintile is the point with 20% of the data below it and 80% above it.

Question 34

Outlier

Answer 34

A value that is outside the expected range

Question 35

Bias

Answer 35

Distorted truth due to error in selecting the study population or in measuring outcome/exposure

Question 36

Validity

Answer 36

Test measuring what is intended to measure

Question 37

Reliability

Answer 37

Consistency of the test

Question 38

Effectiveness

Answer 38

Effect in real life condition

Question 39

Efficacy

Answer 39

Effect in ideal conditions

Question 40

Efficiency

Answer 40

Maximum output with minimum cost

Question 41

Systematic

review

Answer 41

Systematically identifying, selecting and critically appraising of literature on topic of interest

Question 42

Meta-analysis

Answer 42

A statistical method used to combine information from studies addressing the same research question to give an overall summary estimate

Question 43

Blinding

Answer 43

Participants and/ or investigators don?t know to which intervention they have been allocated

Question 44

Randomisation

Answer 44

Random allocation of participants of a study to the intervention or the control group

Question 45

Intention to treat analysis

Answer 45

Analysis according to the groups that participants were allocated to, whether or not they actually received the intervention