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Histogram (bar graph) & Frequency Polygon (line graph)

August 29th, 2009 admin No comments

Histogram

?On the histogram, is the x axis value the left, center or right value of the interval?

Frequency Polygon

The superimposing of the FP upon the histogram would consist of placing a dot at the center of each interval and connecting the dots with a line forming what we traditionally refer to as a line graph.

Here’s an older guide that gives you some pointers for the creation and the result below:

superimposed_graph

Categories: Statistics Tags:

Stem-Leaf (stemplot) and Frequency Distribution in Excel

August 27th, 2009 admin No comments

Stem and Leaf

Here is a pretty decent video from Mike Gel Girvin out of Highline Community College on Stemplot (Stem-Leaf Chart)

The formulae:   =REPT(” 0 “,COUNTIF($A$1:$A$31,D11*10+0))&REPT(” 1 “,COUNTIF($A$1:$A$31,D11*10+1))&REPT(” 2 “,COUNTIF($A$1:$A$31,D11*10+2))&REPT(” 3 “,COUNTIF($A$1:$A$31,D11*10+3))&REPT(” 4 “,COUNTIF($A$1:$A$31,D11*10+4))&REPT(” 5 “,COUNTIF($A$1:$A$31,D11*10+5))&REPT(” 6 “,COUNTIF($A$1:$A$31,D11*10+6))&REPT(” 7 “,COUNTIF($A$1:$A$31,D11*10+7))&REPT(” 8 “,COUNTIF($A$1:$A$31,D11*10+8))&REPT(” 9 “,COUNTIF($A$1:$A$31,D11*10+9))

Yes, that is a big pile of copy paste but you should be able to see the basic breakdown of it: =REPT (the repeat function) (” 4 “, Countif(range, criteria * 10 + 0)

the range consists of the cells you want to make the stemplot of, the criteria is stem number, the * 10 states that it is the tens column with the single digits.

This is a little lengthy and I’m sure we’ll find a better way of handling this.  This option is completely customizable and takes a couple minutes.

For the Frequency Distribution:
Excel Formula: =frequency(data_array, bins_array)

data_array is the set of information (remember to lock the data selection with F4 before dragging formula

bins array is the exact upper limit (just highlight this range)

Here’s and excel doc that I found online (fogot to snag the URL of the original)

excel_basic_statistics

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Categories: Statistics, Uncategorized Tags: