Week 1

Question 1

Five stages of statistical process.

Answer 1

Hypothesis - Question of interest
Study Design - how to collect information
Collect Data
Analyse Date - descriptive statistics (understanding), inference (modelling)
Present Results

Question 2

What are the six principles of statistics?

Answer 2

-collection
-classification
-organisation
-analysis
-interpretation
-presentation of information

Question 3

Explanatory variable.

Answer 3

Piece of information that we are interested in. We observe differences in the explanatory variable and notice whether they are related to the response variable.

Question 4

Define population.

Answer 4

Entire set of objects of interest.

Question 5

Define sample.

Answer 5

Subset of the set of objects of interest.

Question 6

What is statistical inference?

Answer 6

Analysing a sample from a population to make inferences about a population.

Question 7

What is a designed experiment? Give an example.

Answer 7

Researcher exerts control over the experimental units. Researcher gives medicine to some patients placebo to others.

Question 8

What is an observational study? Give an example.

Answer 8

Researcher observes the experimental units and records the variables of interest. E.g. To assess study habits, students are asked how they prepared for an exam and then their grades are compared.

Question 9

What is quantitative data?

Answer 9

Measurements that are recorded on a natural numerical scale.

Question 10

What is continuous data?

Answer 10

Quantitative Data; measurements of which can fall anywhere on the real line.

Question 11

What is discrete data?

Answer 11

Quantitative data; measurements of which can only take one of a finite set of values.

Question 12

What is qualitative data?

Answer 12

Measurements that cannot be recorded on a natural numerical scale.

Question 13

What is nominal data?

Answer 13

Is qualitative data with no meaningful ordering.

Question 14

What is ordinal data?

Answer 14

Is qualitative data with an inherent order.

Question 15

What does a barchart represent?

Answer 15

Shows the distribution of categorical values.

Question 16

What does a histogram represent?

Answer 16

Shows the distribution of numerical values.

Question 17

What does a scatterplot represent?

Answer 17

Shows the relationship between variables.

Question 18

What are bins?

Answer 18

Frequency on the x-axis in a histogram representation.

Question 19

What are the measures of location? (4)

Answer 19

Mean
Median
Mode
Percentiles

Question 20

What are the measures of spread?

Answer 20

Variance
Standard Deviation
Range
IQR

Question 21

Explain box plots.

Answer 21

Median is the horizontal line in the box.
Top of box is 3rd Q
Bottom of box is 1st Q
Arms stretch to 1.5 times 1Q and 3Q respectively.
Dots outside arms represent outliers.

Question 22

Define standard deviation.

Answer 22

Records the root mean squared deviation of values from the mean.

Question 23

What is the relationship between sample standard deviation and sample variance?

Answer 23

sample variance = (sample standard deviation) ^2

Question 24

Formula for sample s.d.

Answer 24

s = root(1/n-1 * (sum (xi - (Xbar)^2)))

where xi is each value. Xbar is sample mean. n is sample size.

Question 25

Formula for s.d.

Answer 25

s = root(1/N * (sum (xi - (X)^2)))

where xi is each value. X is population mean. N is population size.

Question 26

Formula for sample variance.

Answer 26

s = 1/n-1 * (sum (xi - (Xbar)^2)))

where xi is each value. Xbar is sample mean. n is sample size.