For science lover, finding a correlation between human height and foot length is very interesting because you can find interesting fact with only little equipment. If you have a great interest in details, you can even use the information you get for forensic purposes such as getting information you need about a suspect with only knowing their footprints left at a scene. Further analysis using mathematical equation can even provide unique formula.
1. Locate your subject’s foot and measure its length. Take another measurement about your first subject’s height. Repeat this step with remaining subjects. You can reduce margin error of your measurement if you have more subjects in your study which will increase the accuracy of the result.
2. Make a chart with foot length (inches) for the x and foot height (inches) for the y axis. Plot the data
3. Find a line which fit your data the best or use a software to do so. That is a single line that describes your data, a straight one that connects all data with least distance between points and line. Use a ruler to draw the line
4. Find the line direction and find how close the line to the best fit line. If the line goes to the north, you have a positive correlation, but if it goes only a bit and relatively goes to flat axis, you may have a weak positive one.
5. Make an equation for the best fit line. You can use any 2 data points which located in the best fit line. If you can find nothing, make and use a plot of 2 imaginary points on the line. Write the data points as (x,y) coordinate points. At this time, you have 2 data points which we will consider as (x1,y1) together with (x2,y2). Measure the slope by calculating: (?y)/(?x). The equation will be y-y1=m(x-x1). You can use this equation to find the height of your subject based on their foot length.
In an experiment, try to find your margin error by comparing the result you got with the real height. If you got a big enough margin error, try to find where you did your mistakes. As what I’ve said before, try to have a larger amount of subjects in order to increase the accuracy of your measurement. At the other words, you can reduce the margin error. It is very important to have small margin error because any error made in real case will lead you to wrong result and wrong suspect. This is a fatal mistake, especially in medical field and crime scene investigation.