S4M03 Lecture #01 1998-09-11

Histograms and other graphical estimates of probability density

All the following graphs were drawn in Systat from the same data (n = 84 observations). The data are students' marks on a class test out of 30. Would you use a normal density function to describe these data? Why or why not?

Which graphs are the most helpful in revealing the underlying probability distribution? Which are the most helpful in interpreting the data? Which of these graphs can you do in other packages (Splus, Minitab, SPSS, SAS)?

Histogram

Fuzzygram

Frequency Polygon

Box and Whisker Plot

Dot Plot

Dit Plot

Jittered Density

Stripe Plot

Stem and Leaf Plot


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