Research/tests

Question 1

In a paired t-test, what p value shows a statistically significant difference between the samples?

Answer 1

p < 0.05 (5%)

Question 2

In a paired t-test what does the p value represent?

Answer 2

The probability that the difference seen between the 2 groups has occurred by chance

Question 3

Sensitivity vs specificity

Answer 3

Sensitivity - how well a test identifies those with the disease (true positive)

Specificity - how well a test identities those without the disease (true negative)

Question 4

How to calculate sensitivity

How to calculate specificity

Answer 4

Sensitivity = true positive / (true positive + false negative)

Specificity = true negative / (true negative + false positive)

Question 5

Whole genome seq vs karyotype vs FISH vs DNA methylation tests

Answer 5

WGS:
comprehensive, base-pair level analysis, especially undiagnosed rare diseases

Karyotyping:
suspected gross abnormality e.g. whole-chromosome/large structural such as trisomy/translocation

FISH:
targeting specific known genetic abnormality, more rapid

DNA methylation:
Prader-Willi/Angelman syndrome - abnormal methylation plays key role

Question 6

RCT vs case control study

Answer 6

RCT
- prospective
- participants randomised to either receive experimental treatment/control treatment i.e. placebo
- outcomes compared between the 2 groups
- reduces bias as random

Case control
- usually retrospective
- outcomes after treatment compared with outcomes in suitably matched controls
- no randomisation so can be bias

Question 7

Risk measure in cohort studies

Answer 7

Relative risk

Prospective
Follow groups based on exposure to see what diseases develop e.g. non smoker vs smoker lung ca risk
Exposure -> disease

Question 8

Risk measure in case control studies

Answer 8

Odds ratio

Retrospective
Look at people with and without a disease to find prior exposures e.g. lung ca vs healthy controls, looking at smoking exposure
Disease -> exposure