Question

A group of medical researchers was interested in potential gender differences in the concentrations of certain minerals in the blood of older patients, and also in consistency of measurements for these mineral concentrations between laboratories. A retrospective chart review was undertaken of the reported concentrations of several minerals in the blood for a total of 178 subjects aged 65 or older. Variables recorded included the subject’s age, sex, reported calcium level (mmol/L), phosphorus level (mmol/L) and alkaline phosphatase level (IU/L) for each subject and which of six laboratories carried out this measurement. (Note: the laboratories are coded as 1 to 6 in the dataset.) In addition, the researchers recoded subjects’ ages into one of five age groups (65-69, 7074, 75-79, 80-84, 85-89) after the data had been collected.

The researchers wish to produce a plot to explore the possible relationship between phosphorus level and age group among male subjects. Which of the following plots is / are appropriate for this purpose?

(a) A bar chart with five categories, one for each age group.

(b) Side-by-side histograms

(c) Five pie charts, one for each age group.

(d) A scatter plot by groups, with a different symbol for each age group.

(e) Side-by-side box plots. (f) (a) and (c), but not (b), (d) or (e) (g) (b) and (e), but not (a), (c) or (d)

Answer 1

Answer:

(g) b and e but not a,c,d

Explanation:

Given:

i) phosphorus level which is Interval data

ii) Age groups which is Ordinal data

iii) Sex(Male) which is Nominal data

Now,

The researchers wish to produce a plot to explore the possible relationship between phosphorus level and age group among male subjects.

Relationship can be found by plotting Interval data on y-axis and categorical data on x-axis.

So, in this case the following (b) and (e) are appropriate.

(b) Side-by-side histograms

(e) Side-by-side box plots