How To Draw A Stem Plot

When you compare them to histograms or boxplots, stemplots (or stem and leaf plots) are much more simple and straightforward to not just put together simply also to read. This, along with the fact that you don't lose information nigh individual data values is one of the benefits of a stemplot. The only existent downside to selecting a stemplot to stand for your data prepare is that it tin be overly circuitous for large data sets and look kind of goofy if the range of your data set is small (I'll explain this afterward we see how to make one).

So let's utilise the following pocket-size, made-up data prepare to encounter how to make a stemplot.

6	12	4	14	35	33	35	37	eighteen	42
45	38	34	34	42	51	58	50	68	72

Step 1: Pick your "stems" and "leaves"

Each of the numbers in your information set can exist viewed as being made up of two parts: a stalk and a leaf. You lot want to pick it and then that the foliage volition be one digit (the reason for this will make sense in a infinitesimal). For this data fix, the tens digit volition be the stem and the ones digit will be the leaf.

stem and leaf

For single digit numbers, we will use a zero equally a placeholder for the tens digit. The flick below shows how we will think most this for the beginning data value of vi.

stem and leaf 2

Footstep 2: Draw a vertical bar with all of the stems on the left

This step sounds much more complicated than it actually is. We desire to wait at our data set and figure out the smallest and the largest stems. We will count upward without skipping any numbers at all. For this data set:

Smallest value: vi (so the smallest stem is 0)
Largest value: 72 (so the largest stem is 7)

And so on the left of our bar nosotros will write out all the whole numbers from 0 to 7.

stems

That's way easier one time you lot really see it correct? Notice that even though we don't have any information values in the 20s that I nonetheless put a 2 in that location. You shouldn't skip any values!

Pace 3: Put each foliage next to its stalk, in order

For this stride, information technology might exist helpful to put your data set in order from smallest to largest. Here is our original data prepare.

half-dozen	12	4	xiv	35	33	35	37	eighteen	42
45	38	34	34	42	51	58	50	68	72

Here is the aforementioned information set in order from smallest to largest.

4	half dozen	12	14	18	33	34	34	35	35
37	38	42	42	45	50	51	58	68	72

You tin can do this all at in one case, only merely to make sure you see where all the numbers are coming from, permit's exercise it in a couple of steps. First, let's put the iv and 6 on the plot.

stemplot-1

Now you see what I mean past "put the value adjacent to its stem in order". Now to end this, nosotros volition continue the same process. Since at that place are no values with a stalk of ii, we just skip that. Also, whenever at that place are repeats, we volition simply list the leafage part twice. So you don't have to roll, here is the finished stemplot along with the data set.

iv	6	12	14	eighteen	33	34	34	35	35
37	38	42	42	45	l	51	58	68	72

stemplot-finished

Besides, notice that we added a title (though here this is made up data, then it is a boring title!) and a cardinal. Every stemplot should have a key considering it could exist that the data values are decimals and a stem of 3 and a leaf of iv represents 3.4 and non 34! Without a cardinal, how would we know?

Finally, as I mentioned, for some data sets a stemplot might not be as useful. You can probably imagine that if there were thousand data values that this would be tough to read and seem busy. But also, imagine if all of the values had the same stem! What if your data set was 100, 108, 109, 109, 109, 108, 107, 106, 104… well you lot get the idea…? Then your stemplot wouldn't be much better than a list of numbers. There are ways around this (breaking upward the stem into two or three parts) just in the end, it might be better to use something like a dotplot for a information fix like this.