# Investigating the Relationship Between Foot Size and Height

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Investigating the Relationship Between Foot Size and Height

I predict that the taller the pupil is, the bigger their foot size

will be.

Plan

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I’ve been given 60 pieces of data from pupils, about their height and

foot size.

I will be using a piece of software called Fathom where I will place

this information into a scatter graph, to see whether or not my

hypothesis is correct. Fathom will produce a line of best fit on my

graph and tell me what my r-value is. The r-value shows the product

moment correlation coefficient. I am expecting a positive correlation.

To prove that my hypothesis is correct, I am looking for a product

moment correlation coefficient from something between 0 to 1 and the

closer the line of best fit is to 1; the more evidence there is to

back up my hypothesis.

The product moment correlation coefficient is a measurement of the

degree of scatter. It is usually denoted by “r” sometimes referred to

as the “r-value” and “r” can be any value between -1 and +1. It can be

used to tell us how strong the correlation between two variables is. A

positive value indicates a positive correlation and the higher the

value, the stronger the correlation. Similarly, a negative value

indicates a negative correlation and the lower the value the stronger

the correlation. If there is a perfect positive correlation (in other

words the points all lie on a straight line that goes up from left to

right), then r = 1. If there is a perfect negative correlation, then r

= -1. If there is no correlation, then r = 0.

A scatter graph to show the relationship between the height and foot

size of all 60 pupils

[IMAGE]

As I had expected, there is a strong positive correlation on my

scatter graph indicating that the taller someone is, the bigger their

feet size. When you take the square root of 0.69 (to find the r-value)

it results to 0.