Representing And Comparing Data

Question 1

If data is coded using the formula
y = (x - a) / b,

What is the mean of the code given by?

Answer 1

ȳ = (x̄ - a) / b

Question 2

If data is coded using the formula
y = (x - a) / b,

What is the standard deviation of the code given by?

Answer 2

σy = σx / b

Question 3

In coding and data, what is the mean effected by and the standard deviation affected by?

Answer 3

The mean is affected by ALL operations, the standard deviation is ONLY affected by × or ÷

Question 4

What is an outlier?

Answer 4

An outlier is an extreme value that lies outside the overall pattern of data

Question 5

What is cleaning the data?

Answer 5

The process of removing anomalies from the data.

Question 6

What should you do before drawing a box plot?

Answer 6

Remove any anomalies/ outliers

Question 7

On a histogram, where does the frequency density go?

Answer 7

It goes on the vertical axis

Question 8

How do you calculate frequency density?

Answer 8

Frequency density =

frequency / class width

Question 9

In a histogram what are the following proportional to?

1. Bar width
2. Bar area
3. Bar height

Answer 9

1. Bar width ∝ class width
2. Bar area ∝ class frequency
3. Bar height ∝ frequency density

Question 10

When making comparisons between two sets of data, what must you comment on?

And which types of data just pair together?

Answer 10

1. A measure of location (mean/median)
2. A measure of spread (σ/ range/ IQR)
   Use words and values in context

PAIRS:
- Compare mean with standard deviation
- Compare median with IQR