Title: Data analysis
Course: Communicable Diseases Part 1 - Ethiopia (Full)

Data analysis

Data analysis refers to categorising the whole of the data you collected into groups so as to make meaning out of it. For instance you can assess the magnitude of a disease by calculating its prevalence and its incidence from the numbers of cases you recorded and the number of people in the population in your community.

Prevalence rates and incidence rates can also be expressed as 'per 10,000' or 'per 100,000' in much larger populations, e.g. of a region or a whole country.

Prevalence refers to the total number of cases existing in the population at a point in time, or during a given period (e.g. a particular month or year). The number of cases can be more usefully analysed by calculating the prevalence rate in the community: to do this you divide the total number of cases you recorded in a given period into the total number of people in the population. The result is expressed 'per 1,000 population' in a community as small as a kebele. For example, suppose that in one year you record 100 cases of malaria in a kebele of 5,000 people: for every 1,000 people in the kebele, there were 20 malaria cases in that year. So the prevalence rate of malaria in that kebele is expressed as 20 cases per 1,000 people in that year.

Calculating the prevalence rate is more useful than just counting the number of cases, because the population size in your kebele can change over time. The prevalence rate takes account of changes in the number of people, so you can compare the prevalence rates from different years, or compare the rate in your kebele with the rate in another one.

Incidence refers only to the number of new cases of a disease occurring in a given period. The incidence rate is calculated by dividing the total number of new cases of the disease in a certain period of time into the total number of people in the population, and is expressed as 'per 1,000 population'.

If there were 10 new cases of cholera in a kebele of 5,000 people in one month, what is the incidence rate of cholera per 1,000 population in that period?

Show answer

The incidence rate in this example is two new cholera cases per 1,000 population.

As a health professional working in a community affected by several health problems at the same time it is difficult to address all the problems at once. Therefore, you should give priority to the most important ones first. But how do you prioritise? You are going to see how to do that next.