Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

G's Phase 1 > Stats/ critical numbers > Flashcards

Stats/ critical numbers Flashcards

1
Q

what is a case control study

A

Find people with disease and controls look back in time for exposure

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

what are the pros of case control

A
  • Good for rare outcomes
  • Fast cheap
  • Few ethical considerations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

cons of case control

A
  • cannot prove causation/ eliminate confounding factors
  • difficult to establish event order
  • subject to recall bias
  • only investigate single disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe cross sectional study

A

Sample a population and count number of affected and unaffected people

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

pros of cross sectional

A

generates hypothesis
cheap fast
few ethical considerations

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

cons of cross sectional

A

cannot prove causation/eliminate confounders
less suitable for rare disease
doesn’t establish event order
sample bias could occur

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

what the cohort study do?

A

take a population monitor those with and without exposure for linked outcome
prospective

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

pros of cohort study

A

event sequence clarity

few ethical considerations

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

cons of a cohort study

A 
Cannot rule out confounding factors
not suitable for rare disease 
time consuming and expensive 
requires follow up - could be difficult 
patients can change behaviors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wat do be a randomised controlled trial

A

multiple group organised into arms given different exposures/treatments and comparing outcomes.
Arms can be balanced by matching, randomising, cross-over, placebo, and blinding.

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

pros of RCT

A

gold standard in proving causation and eliminating confounding factors and bias

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

cons of RCT

A

expensive time consuming
not good for rare diseases
ethical approval trickier as gold standards are often unethical
requires compliance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is ecological study?

A

using massive samples to look at trends across populations not individuals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

pros of ecological

A

fast cheap
large sample
easy
good first step for hypothesis generation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

cons of ecological

A

don’t know how data was collected
data may be missing
doesn’t prove causation
correlation not causation - ecology fallacy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what are the types of sampling

A 
random
systematic
convenience
cluster 
stratified
17
Q

lead time bias

A

illness detected sooner but no difference in treatment outcome

18
Q

length time bias

A

people who live with disease for longer more probable to be screened - false impression of screening improving survival

19
Q

what is risk

A

risk is probability

eg risk of rolling a 6 is 1/6

20
Q

how do you calculate number needed to treat/harm (NNT/H)

A

1/ absolute risk difference

must always be rounded up

21
Q

how to calculate odds

A

x/(n-x)
x=outcome
n=sample size
with/without

22
Q

how to calculate sensitivity

A

true positive/all population with disease

true pos/(true pos + false pos)

23
Q

how to calculate specificity

A

false positive/all healthy patients

think who is healthy but have been told they’re ill

24
Q

positive and negative predictive value

A

disease pos/all who’s results were pos

disease neg/ all who tested neg

25
Q

test accuracy how to calc

A

all correct results/ total tests performed

             all results
26
Q

standard deviation equation

A

root of [sum of (each value-mean)^2 / n-1]

27
Q

standard error is?

A

standard deviation / n^(1/2) [which is square root n]

28
Q

when is interquartile range used and how is it calculated?

A

when data is skewed
upper quartile - lower quartile
Q3-Q1

29
Q

what is a 95% confidence interval

A

a range we are 95% sure the true population lies in

30
Q

how to calc 95% confidence interval?

A

mean +or- 1.96*SE

31
Q

what is correlation?

A

simple association - no causation

32
Q

when to use regression

A

when a change in one variable can predict another

33
Q

what is a test for correlation

A

pearson’s correlation coefficient
1 pos
-1 neg
0 nil

34
Q

when is a logistic regression best used

A

outcome is binary
log(outcome)= a + bx
a is where prob increases
b is how fast it increases

35
Q

Carried out in a snap-shot of time without follow-up of subjects or looking back in time

A

Cross Sectional

36
Q

Collect information now and follow subjects up over time to explore outcomes

A

Cohort

37
Q

Collect information on an outcome now, and look back in time to see what exposures were experienced

A

Case-Control

38
Q

Information on groups of individuals (e.g. countries) rather than individual level data

A

Ecological

G's Phase 1 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions