Studies Flashcards
What is correlation?
When a change in one variable is accompanied by a change in another variable, but does not necessarily mean they are causally linked
What is an example of correlation?
There is positive correlation between the number of cigarettes smoked over a lifetime and the chance of developing cardiovascular disease
What is causation?
When a change in one variable is responsible for a change in another variable
What is an example of causation?
Speaking English as your first language correlates well with having a greater than average life expectancy
What is a cohort study?
They follow a large group of people over time to see who develops the disease and who does not
What type of study is a cohort study?
Prospective; at the start of the study none of the participants have the disease
What happens during a cohort study?
People’s exposure to suspected risk factors and whether they develop the disease is recorded so any correlations between the factors and disease development can be identified
What are disadvantages of a cohort study?
It may take a long time for the condition to develop so these studies can take years and be very expensive
How are cohort studies used for CVD?
Every two years the participants are asked to provide a detailed medical history, undergo a physical examination and tests, and answer questions about their lifestyle
What major CVD risk factors were identified from the cohort study?
• High blood pressure
• High blood cholesterol
• Smoking
• Obesity
• Diabetes
• Physical inactivity
What is a case-control study?
A group of people with a disease are compared with a control group of individuals who do not have the disease
What type of study is a case-control study?
Retrospective; participants already have the disease
What happens during a case-control study?
Information is collected about the risk factors that they have been exposed to in the past, allowing factors that may have contributed to development of the disease can be identified
What are features of a good study?
• Clear aim
• Representative sample
• Valid and reliable results
• Sample size
• Controlling variables
