Statistics

Question 1

What are the 2 main variable types?

Answer 1

Categorical and quantitative

Question 2

What two sub categories can categorical data be divided into?

Answer 2

Nominal and ordinal

Question 3

Why are the characteristics of nominal data?

Answer 3

Unordered, labelled characteristics
Binary - variable has just 2 categories
E.g. Blood group (a/ab/o/b)

Question 4

What are the characteristics of ordinal data?

Answer 4

Small set of ordered (ranked) categories
May be labels, numbers or both
Eg disease severity - none/ mild/ moderate/ severe

Question 5

What are the characteristics of quantitative data?

Answer 5

Values have quantitative meaning
Higher number = more there is of it
E.g. Age in years or weight in kg

Question 6

What type of data is marital status? (Binary, nominal, ordinal or quantitative)

Answer 6

Nominal

Question 7

What type of data is body temp? (Binary, nominal, ordinal or quantitative)

Answer 7

Quantitative

Question 8

What type of data is age in year intervals? (Binary, nominal, ordinal or quantitative)

Answer 8

Ordinal

Question 9

What type of data is hypertension status (yes or no)? (Binary, nominal, ordinal or quantitative)

Answer 9

Binary

Question 10

Define standard deviation

Answer 10

Average difference between scores and the mean

Question 11

What percentage of the data does the interquartile range span?

Answer 11

The middle 50% of scores

Question 12

What is the symmetry of a data set?

Answer 12

For each person that has a score below the median, there is someone with a score above it

Question 13

Give 3 ways you could graphically summarise quantitative data, and what characteristic of these data does this asses?

Answer 13

Histogram, dotplot and box & whisker

Assesses if it’s parametric/ non parametric (the normal distribution)

Question 14

If a box and whisker plot is positively skewed, how would the graph look different to that representing a normal distribution?

Answer 14

Top box thicker than the bottom box

Top whisker would be longer

Question 15

If the data is symmetrical (normally distributed) what values do you report?

Answer 15

Mean (average) and standard deviation (variation)

Question 16

If the data is asymmetrical (not normally distributed) what values do you report?

Answer 16

Median (average) and interquartile range (variation)

Question 17

Inferential statistics use sample data to make inferences about characteristics in the whole population.
Name three types of values used in inferential statistics

Answer 17

Standard errors, confidence intervals, p values

Question 18

What does standard error indicate?

Answer 18

How far on average the sample estimate is expected to be from the true population parameter value

Question 19

Does standard error quantify accuracy or precision of the estimate?

Answer 19

Precision

Question 20

What does a smaller standard error value show?

Answer 20

The closer the sample estimate is likely to be to the true value within the population

Question 21

Does standard deviation measure sensitivity or variability of observations within the sample?

Answer 21

Variability

Question 22

Define confidence interval

Answer 22

A range of values within which we can be certain with some degree of confidence that the true population parameter lies

Question 23

What does the 95% confidence interval summarise in comparison to the 95% range?

Answer 23

95% confidence = Precision of the estimate

95% range = variability of observations within a sample