POPH192 Lecture 23 - Chance I

Question 1

what are the 3 types of internal validity?

Answer 1

1) chance
2) bias
3) confounding

Question 2

what is external validity?

Answer 2

the extent to which the findings of the study can be applied to a broader population (also known as generalisability)

Question 3

what is internal validity?

Answer 3

the extent to which the findings of the study are free of chance, bias and confounding
-are there any other explanations for the study findings other than them being right

Question 4

what is the population parameter?

Answer 4

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

Question 5

what is the sample estimate?

Answer 5

the studies estimate of the parameter

-the measure found in the studies sample sometimes called the point estimate

Question 6

what is the effect of increasing the size of the study sample when randomly sampling?

Answer 6

• reduces sample variability (standard deviation etc)
• increases likelihood of getting a representative sample
• increases precision of parameter estimate

Question 7

how can you reduce sampling error?

Answer 7

by increasing the sample size

Question 8

what is a confidence interval?

Answer 8

we are 95% confident that the true population value lies between the limits of the confidence interval

Question 9

what is the statement used for a confidence interval in a question?

Answer 9

we are 95% confident that the true odds ratio lies between … and …

Question 10

what is the relationship between width and precision?

Answer 10

width indicates precision

• narrow CI = more precise
• wide CI = less precise

Question 11

how do you make the CI narrower?

Answer 11

increase the sample size

-this is a fundamental concept