Chance I

Question 1

What is internal validity?

Answer 1

Internal validity is where we have a source population that has an actual measure of occurrence we want to find out about. To estimate this we need to take a smaller study population from our source population which gives us an estimate of the occurrence

Question 2

What is external validity?

Answer 2

Extent to which you can take the study findings and apply them to a broader or different population, also known as generalisability
Judgement depending on what is being studied and who it being applied to

Question 3

How does estimate relate to parameter?

Answer 3

Measure of occurrence/association (value we get in our study) that is our study estimate is used to estimate the parameter, the ‘truth’ of the measure of association

Question 4

What is chance?

Answer 4

Chance is where if you repeatedly sampled randomly from the same source population, most of the time you would get a sample that is similar to your other sample however some of the samples would be quite different just by chance. This is called sampling error and is a form of random error

Question 5

To improve our confidence in the study we can:

Answer 5

Increasing the size of the study sample when randomly sampling as this reduces sample variability, increases likelihood of getting a representative sample and increases preciousness of parameter estimate

Question 6

What are Confidence intervals?

Answer 6

If you repeated a study 100 times with random sample each time and got 100 estimates and 100 confidence intervals, in 95 of the 100 studies the parameter would lie within the study’s 95% confidence interval but in 5 of the studies the parameter would not lie within the study’s 95% CI
Increases sample size narrows the CI

Question 7

What is the clinical importance of confidence intervals?

Answer 7

Confidence intervals can help us decide whether the study findings are clinically important or not
If the CI meets the clinical importance threshold of below 0.9 then it is important, if above 0.9 it is not it is not clinically important

Question 8

What is the Parameter?

Answer 8

The true value of the measure in the population that the study is trying to discover

Question 9

What is the Estimate?

Answer 9

The measure found in the study sample, sometimes referred to as the point estimate