Statistics

Question 1

case-control study

Answer 1

• observational study
• investigates the cause of a disease when comparing people with and without that disease
• starts with a disease of interest and selects patients with that disease for study
• then selects group without the disease to compare
• often sample sizes of the two groups are similar
• cases and controls are then compared to discover possible causal factors
• retrospective study

Question 2

cohort study

Answer 2

• an observational study that aims to investigate causes of a disease
• longitudinal, starting with an unselected group of subjects who are then followed up for a set period of time
• usually prospective, where risk factor data is collected before the person gets the disease
• aims to discover if there are particular aetiological factors causing a disease in the future

Question 3

cross-sectional study

Answer 3

• observational study
• a sample group is chosen and data from an individual is collected at one point in time only
• surveys are observational studies

Question 4

randomised control trial

Answer 4

• experimental study
• prospective and longitudinal
• assess efficacy of treatment or intervention
• compares outcomes in a group of patients treated with a new therapy, and those in a comparable group of patients with a control therapy; placebo
• patients in both groups randomised, enrolled, treated and followed over same time period
• gold standard study design; tests between two variables allowing for direct comparison of two groups, and controlling for confounding factors through randomisation. this test also reduces bias as it can be blinded

Question 5

absolute risk

Answer 5

.

Question 6

relative risk

Answer 6

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Question 7

absolute risk reduction

Answer 7

.

Question 8

relative risk reduction

Answer 8

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Question 9

number needed to treat

Answer 9

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Question 10

number needed to harm

Answer 10

.

Question 11

sensitivity

Answer 11

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Question 12

specificity

Answer 12

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Question 13

positive predictive value

Answer 13

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Question 14

negative predictive value

Answer 14

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Question 15

p-value

Answer 15

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Question 16

95% confidence interval

Answer 16

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