Prevalence And Incidence Flashcards

1
Q

Define Prevalence, how is it calculated and expressed?

A

A measure of how common a disease is

Number of people with condition / number of people in total

As a % or number/n people

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 types of prevalence?

A

Point prevalence - % in specific moment in time

Period - % over a period eg month

Lifetime - % that will suffer with that disease during lifetime

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define Incidence, how is it calculated and expressed?

A

Rate at which new events occur in a population, over a defined period of time

Number of new cases / number of people in total x years observed

As per n people per time period (eg 100 cases per 1000 people per year)
Or per n person-years (100 cases per 1000 person-years)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What factors affect prevalence?

A

Incidence rate
Recovery rate
Death rate
Transfer rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Give examples of conditions with:

High prevalence + High incidence
High prevalence + Low incidence
Low prevalence + High incidence
Low prevalence + Low incidence

A

High prevalence + High incidence: common not brief condition (common cold)

High prevalence + Low incidence: uncommon, long term condition (Type 2 Diabetes)

Low prevalence + High incidence: common, brief condition (nose bleeds)

Low prevalence + Low incidence: uncommon, short term condition (pancreatic cancer)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What’s statistical inference?

A

Best guess based on data of the true value and describe the level of uncertainty

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What’s point estimation?

A

Best guess based on sample data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is sampling error and how can it be reduced?

A

Difference between sample point estimates and the true value

Reduce by testing a larger population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What’s standard error? How can it be reduced?

A

Numerical value representing the sampling error

Small SE = best guess closest to the truth and will get small value from a larger sample size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are confidence intervals? How are they usually expressed?

A

Should present estimates from a sample with a range of plausible values to represent the level of uncertainty

The study finds 80% of mothers hold their baby on the left. A 95% CI is 75-85%
“You can be 95% confident that the true value lies between 75-85% of new mums holding their baby on the left”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What effect does a larger sample size have on:
Sample error
Standard error
Confidence intervals

A

Reduces both sample and standard error and provides narrower confidence intervals = estimate closer to the true value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can confidence intervals be compared?

A

To see if there is a statistically significant (real) difference between two groups

If CI overlap = statistically significant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly