Association: in statistics, the concept of association quantifies the relationship between two or more variables. For example, there is an association between smoking and lung cancer.

Cohort studies: non-experimental or observational study design. In a cohort study, data from a large group of people sharing common characteristics is regularly collected and analysed over a long period of time.

Incidence: frequency at which individuals within a specific population develop a given symptom or quality. Ex: cancer incidence in the UK is 363,000 new cases every year.

Meta-analysis: quantitative statistical analysis of several separate but similar experiments or studies in order to test the pooled data for statistical significance (Merriam-Webster).

Mortality: indicate numbers of deaths by place, time and cause.

Morbidity: the state of being symptomatic or unhealthy for a disease or condition. It is usually represented or estimated using prevalence or incidence.

Prevalence: proportion of the population living with a given symptom or quality. Ex: cancer prevalence in the UK was 2.5 million on 31/12/2015.