EPIDEMIOLOGY - Biostatistics

Question 1

What are the two types of statistics?

Answer 1

Descriptive statistics
Inferential statistics

Question 2

What are the two types of data?

Answer 2

Quantitative
Qualitative

Question 3

Describe the two types of quantitative data

Answer 3

Continuous: data that does not have fixed values
Discrete: data that has fixed values

Question 4

Describe the two types of qualitative data

Answer 4

Nominal: distinct, unordered categories of data
Ordinal: categories of data with some order or hierarchy

Question 5

What are probabilistic outcomes?

Answer 5

Probabilistic outcomes are the degree of randomness resulting from the result of an experiment or trial

Question 6

What are the measures of central tendency?

Answer 6

Mean
Median
Mode

Question 7

What are the measures of dispersion?

Answer 7

Max and min values
Standard deviation
Interquartile range

Question 8

In practice, which combinations of central tendency and dispersion would you typically report?

Answer 8

1. Mean and standard deviation
2. Median and interquartile range

Question 9

What is the purpose of frequency tables?

Answer 9

Frequency tables summaries the frequency of each possible value in data collection

Question 10

What is the difference between continuous and relative frequency?

Answer 10

Continuous frequency: running total of frequencies in a frequency distribution
Relative frequency: ratio of the frequencies (%)

Question 11

Give six examples of graphs that can be used to visualise data

Answer 11

Box plots
Bar plots
Density plots
Pie charts
Scatter plots
Line plots

Question 12

What is the null hypothesis?

Answer 12

The null hypothesis is a statement in which there is no relation between the two variables

Question 13

What is the alternative hypothesis?

Answer 13

The alternative hypothesis is a statement in which there is some statistical relationship between the two variables

Question 14

What is statistical hypothesis testing?

Answer 14

Statistical hypothesis testing is the use of data to determine the plausibility of a hypothesis

Question 15

What is a test-statistic (T-statistic)?

Answer 15

A test statistic (T-statistic) is a number calculated by a statistical test which describes how far your observed data is from the null hypothesis

Question 16

What is the probability value (P-value)?

Answer 16

The probability value (P-value) calculates the likelihood of your test statistic (T-statistic) to tell you how likely it is that your data could have occurred under the null hypothesis

Question 17

Describe how a 0.05 probability value (P-value) works in regards to the null hypothesis?

Answer 17

A p-value less than 0.05 is typically considered to be statistically significant, in which case the null hypothesis should be rejected. A p-value greater than 0.05 means that deviation from the null hypothesis is not statistically significant, and the null hypothesis is not rejected

Question 18

What is the main difference between parametric and non-parametric tests?

Answer 18

Parametric tests compare the mean values of normally distributes data and non-parametric tests compare the median values of abnormally distributed data

Question 19

What are four examples of parametric tests?

Answer 19

One sample t-test
Two sample t-test
Paired sample t-test
Analysis of variation (ANOVA) test

Question 20

When would you use a one sample t-test?

Answer 20

To compare the mean value of a sample with an expected mean value

Question 21

When would you use a two sample t-test?

Answer 21

To compare the mean values of two different samples

Question 22

When would you use a paired sample t-test?

Answer 22

To compare the mean values of two paired samples

Question 23

When would you use an analysis variance (ANOVA) test?

Answer 23

To compare more than two mean values with eachother

Question 24

What is the corresponding non-parametric test to a one sample t-test?

Answer 24

Wilcoxon Signed Rank test

Question 25

What is the corresponding non-parametric test to a two sample t-test?

Answer 25

Mann-Whitney test

Question 26

What is the corresponding non-parametric test to a paired sample t-test?

Answer 26

Wilcoxon Signed Rank test

Question 27

What is the corresponding non-parametric test to an analysis variation (ANOVA) test?

Answer 27

Kuscall-Willis test

Question 28

When would you use a Chi-squared test?

Answer 28

To compare the proportions of categorised data

Question 29

What is a 95% confidence interval?

Answer 29

A 95% confidence interval is a range of values above and below the point estimate within which the true value is likely to lie with 95% confidence

Question 30

What is the correlation coefficient?

Answer 30

The correlation coefficient in the measure of a relationship between two numerical values

Question 31

What is represented by the correlation coefficient value of 1?

Answer 31

1 = Perfectly correlated (as one value increases, the other variable also increases)

Question 32

What is represented by the correlation coefficient value of 0?

Answer 32

0 = No correlation (no association between the variables)

Question 33

What is represented by the correlation coefficient value of -1?

Answer 33

-1 = Perfectly anti-correlated (as one value increases, the other variable decreases)

Question 34

What is linear regression analysis?

Answer 34

Linear regression analysis is the prediction of the value of a variable based on the value of another variable

Question 35

What are the two parameters estimated by linear regression analysis?

Answer 35

Intercept and gradient

Question 36

What is extrapolation?

Answer 36

Extrapolation is the prediction of a new Y-value from an X-value outside the range covered by given data

Question 37

What is intrapolation?

Answer 37

Extrapolation is the prediction of a new Y-value from an X-value within the range covered by given data