Introduction to Epidemiological Study

Question 1

Define Epidemiology

Answer 1

Study of the distributuon and determinants of health related states

Application of this study to the control of diseases and other health problems

Question 2

How can the distribution of helath-related states be investigated?

Answer 2

Surveillance and Descriptive Studies

Question 3

How can the determinants of helath-related states be investigated?

Answer 3

Analytical studies

Question 4

Define statistics

Answer 4

The collection, presentation, description and analysis of data

Measurable in numerical forms

Question 5

What is the purpose of statistics?

Answer 5

The puropse is to generalise to the population

Question 6

What is the difference between statistics and probability?

Answer 6

Question 7

What is the sampling error?

Answer 7

The expected and normal distribution in the samples obtained from a given population

(each time you take a sample of people from the population, you will get a very slightly different range of people)

Question 8

What does the prevalence tell you?

Answer 8

The proportion of individuals affected by the condition at a single point in time

• form of cross-sectional survey*
• e.g. today 80 out of 1,500 people have cancer, 80/1500 = 5.3%*

Question 9

What does the incidene rate tell you?

Answer 9

The number of new cases of health-related issue

Question 10

What is required to calculate an incidence rate?

Answer 10

Number of affected individuals

Study poplulation size

Time dimension (between start and end date)

Question 11

Calculate the incidence rate of heart attacks amongst factory workers in this example:

300 heart attacks in 50,000 factor workers between July 2015 and December 2016 (1.5 years)

Answer 11

300/50,000 = 0.006 heart attacks per worker in 1.5 years

i.e 6 heart attacks per 1000 workers in 1.5 years

6/1.5 = 4 hear attacks per 1000 workers per year

Question 12

What is the formula used to create incidence rate?

Answer 12

Question 13

How do you calculate incidene rate using person years?

Answer 13

Mutiple the number of individuals, by the length of time (in years) over which they were followed up

Add all the values together to create the total number of person years

• e.g. 1 person followed up over 10 years +*
• 3 people followed up over 2 years +*
• 7 people followed up for 0.1 years*
• = (1x10) + (3x2) + (7x0.1) = 16.7 person-years*

Question 14

What is the forumula used to calculate prevalence?

Answer 14

Prevalence = incidence x duration of disease

Question 15

What would lead to a decrease in prevalence?

Answer 15

Curing Patients

Death of Patients

Question 16

Why may an observed quantitiy be different to the true values?

Answer 16

May be due to random variation in the samples selected from the population

Question 17

What information can an observed value provide during analytical research?

Answer 17

A best estimate of the true value

Question 18

What is a null hypothesis?

Answer 18

A hypothesis assuming that two things are equal or that there is no effect or difference