Scatterplot & Interpretation

See Like a Scientist:

Scatterplot & Interpretation:  it’s as easy as 1,2,3

Introduction:

Up until now our strategies for helping you see like a scientist have focused on how you perceive the visuals, how do shape, color, and representation affect your ability to interpret. In addition, we have given you some basic advice about the need to read and understand items like the title, the axes, and the legend.  So, far we have not really discussed how to think about reading the information in a graph.  For this discussion we are going to focus again on the scatterplot (introduced earlier in the axes exercise).  

How to interpret? 

One way to think about interpretation is looking at the different levels of how the data are layered. 1.  The most basic component of any scatterplot is thinking about what does a single point represent?  2.  What possible patterns or trends can you see among the points?  3.  What does the entire visual mean?

If we use this system on an example, it might look like this (a completely fictionalized data set). 

1. Interpret a point:  In this example the circle shows what identifying what a single point means.  To do this you need to read the axes.  This point represents one person who is 37 years old and who has eaten 69 donuts.

2.  The red line in the image represents a trend, in that the older you get, this data shows the fewer donuts you eat.  There can be multiple trends in a plot, and you should try and identify as many as possible to help you with …

3.  …Interpreting the overall message of the graph!  Ideally the title of the visual will tell you what the visual shows, but many times it may be absent or lack the necessary information to help with interpretation.  So, if left to our own devices, we might say that the overall message is that as you get older you consume fewer donuts.  But looking for other patterns we see that there are only two points for individuals who are under 30 years of age.  So this may inspire us to see how the data were collected (we might find it was a survey of professors at … some random midwestern university…who like donuts; hence the few individuals under 30 [although that then begs the question who is this 9 year-old professor]).

Trying to resolve all of the trends and synthesize the information is the power behind visuals.  This is the higher order thinking that occurs when you try and interpret a visual that we mentioned in the intro to this exercise. 

Lesson:  Identifying a point on visual is a good start and skill.  Interpreting a trend on a visual is better and allows you to start making predictions.  Evaluating the overall message is best, and it is what you should strive for to be able to see like a scientist.