Stats / Data

Question 1

Whats an ogive

Answer 1

A continous cumulative frequency curve whereby the central point had 50% of values above it and 50% of values below it
i.e. the interquartile range lies between the first and third quartiles

Question 2

Types of data from a sample

Answer 2

Qualitative
Quantitative

Question 3

Quantitive data can be of two types

Answer 3

Numerical
Categorical

Question 4

Numerical data can be either

Answer 4

Discrete - distinct values within a range
Continuous - any values within a range

Question 5

Categorical data has three subcategories

Answer 5

Binary (two levels only)
Ordinal (more than two levels with a specific order i.e. low medium high)
Nominal (more than two levels with no order e.g. ethnicity)

Question 6

What is the Chi square test

Answer 6

A statistical test that can be used to determine wether observed frequencies are significantly different from expected frequencies
Outcome allows to accept or reject the null hypothesis
Used to compare discontinous categorical data

Question 7

When is a binominal test used

Answer 7

To see if observed test results differ from what is expected
Used when there are two possible outcomes e.g. success or failure and you have to estimate what the probability of success is

Question 8

When is the paired t-test used

Answer 8

when a group is measured twice i.e. each individual has two repeated measures

Question 9

Whats an unpaired t test for

Answer 9

looks at the differences between two groups on a variable of interest
a normal distribution and normal standard deviation are assumed

Question 10

What is regression analysis

Answer 10

Generates an equation to describe the statistical relationship between one or more predictor variables and a response variable
Used to determine hwo one variable correlates with another

Question 11

When is a box and whisker plot used

Answer 11

Depicts a range of values including a sample minimum, lower quartile, medium, upper quartile and sample maximum
Box extends from border of the lower quartile to the border of the upper quartile, with the median depicted as a horizontal line across it

Question 12

How to work out the relative risk?

Answer 12

Incidence of the disease in the exposed group DIVIDED BY incidence of the disease in the NON exposed group

Question 13

What has the biggest impact on interpretation of meta analyses and why

Answer 13

Publication bias
There is a tendency to only submit positive trials and for journals to favour publication of positive studies
This can lead to an over estimate of effect size of a particular intervention vs a single, large, well conducted study

Question 14

How to do a calculation of number needed to treat

Answer 14

Big number take away small number
Divide into 100

Question 15

How to calculate sensitivity

Answer 15

Dividing the true positives by the true positives plus the false negatives