Simple Histograms with R Software



Getting Started, Loading Data
I called my data data1

I might first be curious about basic descriptive & summary statistics about your data.

By typing str(data1),  you can see that the R object "data1", has three variables; section, class & final. (This happens to be data of student section attendance, lecture attendance and final exam scores for a class at Michigan State University.) 


Simple Histogram
Let's create a histogram for their final exam grades:
hist(data1$final)
This says, "draw a histogram by going into 'data1' and looking at the column 'final'". Note that you need the dollar-sign to link your R object 'data1' to the variable 'final'.

We get the following histogram:


Notice that there are only 9 bins to form the histogram above. 
Since the maximum score was 166 points. let's set 166 bins so we have a vertical line for each possible exam score. 

Adding More Bins (Adding more detail to a histogram)
hist(data1$final,166)


Well, it doesn't look great (I think my screen resolution was just really bad as I took the screen shot), but has a bit more information in it. 

Adding Labels to a Histogram in R
Now, let's add some useful labels: 
hist(data1$final,100, main="Final Exam Test Scores", xlab="Exam Scores", ylab="Frequency")


















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