To demonstrate these steps we need to start with some data. We will use the GNRND4 program on the calcualtor to generate this data.
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Before we do anything we will make sure that the calculator is cleared of
any old data that happened to be on it already. By using the
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This pastes the ClrAllLists command onto the main screen.
We press teh ![]() |
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Next we press ![]() ![]() |
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This pastes the command SetUpEditor onto the main screen.
We press the ![]() |
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Once the calculator is cleared and set up we start the GNRND4 program.
(Note that this page was created using version 1.1 of that program.)
We provide the key values to the program.
Note that the second key in this case is quite long. It is so long that it extends to a second line.
You will not get the correct results if you omit the finl two 0's in 500515300200.
Then we press
The program will give a few intermediate screens before it finally displays the list that it generated, as shown in Figure 6. |
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Here we see the start of the list of values. We can use the
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After reviewing all the numbers, we
press ![]() |
We will generate the same list of values here. As noted in Figure 5, we generated the list of data on the calculator using GNRND4 with Key 1=1125735009 and Key 2=500515300200. That list, shown in Figures 6 and 7, has the same numbers that appear in the following table:
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Continuing with the calculator, we press ![]() ![]() The command that we want is the first one, 1-Var Stats.
We press | ||||||||||||||||||||
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The 1-Var Stats command, when given by itself, will do an analysis of
the values in L1. That is exactly where the GNRND4
program put our numbers. Thus, we are ready to perform the command.
To do that we press the ![]() | ||||||||||||||||||||
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The calculator does the analysis and then provides 11 lines of output, the first six of which are immediately
available on the screen. Here we see that the mean of the data is 37.21372549 to 10 significant digits.
(There is little chance that we really need so many digits, but the calculator is happy to provide them
anyway.)
The next line, The line | ||||||||||||||||||||
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The remaining values are the five quartile points:
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A Box-and-whisker plot gives a graphic representation of
the five
quartile values noted above. To get that Box-and-whisker plot we return to the
STAT PLOT menu via the
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Figure 13 shows the Plot1 settings before we have made any changes to them.
We want to change the Type: setting from histogram, shown selected as
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To make this selection we move the cursor to the desired spot,
shown in Figure 14, and then press ![]() ![]() ![]() | ||||||||||||||||||||
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After we set the Type: to the ![]() | ||||||||||||||||||||
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The Box-and-whisker plot for our data is shown here. We recall the values that we saw above.
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As a small demonstration of another calculator capability, we can move into
TRACE mode by pressing the ![]() | ||||||||||||||||||||
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One of the concerns that we always face is that of identifying any outliers in the data.
Our "rule" for doing this is to first compute an intra-quartile range (IQR) as the value of
Q3–Q1, or in this case, 41–35=6.
Then we take 1.5 times that value, (1.5)*6=9 and we use that value to set limits, one below
Q1 and one above Q3. In this particular case
that puts us at Q1–9=35–9=26 and
Q3+9=41+9=50.
These are the lower and upper limits, respectively. Any data values outside
of those limits are considered outliers. For our data set we immediately know tat
we have at least one such outlier because
the minimum data value is 25.2 which is below the lower limit that we found,
namely, 26.
There is a modified Box-and-whisker plot that depicts the lower and upper limits.
We return to the STATS PLOT menu,
via | ||||||||||||||||||||
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In the Plot1
screen we have moved the highlight to the ![]() ![]() | ||||||||||||||||||||
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Having made the selection we return, via ![]() ![]() | ||||||||||||||||||||
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The display is now that of the modified Box-and-whiskerr plot. Note that the "whiskers" only extend to the ends of the lower limit (Q1–1.5*IQR) and the upper limit (Q3+1.5*IQR). Furthermore, the one outlier in our data set is identified by a mark beyond the "whisker". | ||||||||||||||||||||
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It might be interesting to now view the same data with a historgram.
To change our plot to such a histogram we first return to the
STAT PLOT menu via ![]() ![]() ![]() | ||||||||||||||||||||
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This capture of the Plot1 settings is after we have moved
to the ![]() ![]() ![]() | ||||||||||||||||||||
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Use ![]() ![]() | ||||||||||||||||||||
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Here is the graph of the data. | ||||||||||||||||||||
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Here we have pressed the ![]() | ||||||||||||||||||||
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We use the cursor keys to change the column selection.
In Figure 27 we have moved the selection to the rightmost column.
THe calculator chose the breakpoints for the columns. We may want to set up different breakpoints.
To do this we press
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These were the values that the ZoomStat action derived from the data in L1. We can change any of these. | ||||||||||||||||||||
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We will reorganize the chart by having the first column start at 25 and setting the column width to 5. That means, if we want the maximum value, 50, to be in a column, then we will need to have a final column tha tgoes from 50 to 55. Therefore, we want to set the Xmax value to 55. | ||||||||||||||||||||
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Press ![]() There is an obvious problem with this histogram. the third column is off the screen. We cannot see the top of that column. We can move into TRACE mode to gather more information. | ||||||||||||||||||||
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Figure 31 shows the calculator in TRACE mode and after we have
used ![]() | ||||||||||||||||||||
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We use ![]() | ||||||||||||||||||||
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We have made three changes here. We changed the column width to 4. THis will give us 7 columns. We have changed the max value to 53, corresponding to the 7 columns. And, we have changed the Ymax value to 25. This will accomodate the 24 items that we found earlier, but we should remember that by changing the column width we will probably change the number of items in each column. | ||||||||||||||||||||
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Returning to the histogram by pressing ![]() | ||||||||||||||||||||
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Moving back into TRACE mode, via the ![]() | ||||||||||||||||||||
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Here we have started the COLLATE3 program. It asks for the
location of the data. We respond with
L1.
Then press | ||||||||||||||||||||
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The program reads all the data and reports that the lowest value found
was 25.2 and the highest was 50. Using its own "strange"
algorithm, the program suggests a starting value
for our first class should be 23.65. We, however, want our first class to start at 25.
We enter that value and press ![]() | ||||||||||||||||||||
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The program responds by suggesting a class (column) width
of 3.1, but we want to use a class width of 4.
We enter that value and press ![]() | ||||||||||||||||||||
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The output from the program gives us the same values
that we got from 1-VAR STATS back in Figure 10
but this time those values have been rounded to 2 decimal places.
The COLLATE3
program is still running at this point, but it is in a paused
condition, waiting for us to press
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Figure 40 has the rest of the output from the program.
So far it does not look like there is much advantage to running COLLATE3. However, that program does much more than just produce the out we have seen. In particular, that program creates six lists of values and it sets the StatEditor to display those lists when the user chooses the Edit... option in the STAT nebu. | ||||||||||||||||||||
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We press ![]() ![]() | ||||||||||||||||||||
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The StatEditor opens showing the values in three lists, along with
the name of each list. The highlight is on the first item in the first list.
The name and index of that item is shown at the bottom of the page along with the value
that is in that indexed position of that list. Each row of data, i.e., each of the list items with a the same index number, represents attributes of the class associated with the given index. Thus, reading across the first data line in Figure 43, we see that the first class starts at 25, that 7 of the values in L1 fall into the first class, and that 0.13725 (i.e., 13.725%) of the values are in this first class. Because the second class has a LOW value of 29 we know that the first class is really values 25≤x<100. Remembering that each "row" across the various lists holds the attributes of a single "class" (i.e., grouping) of values in the original user specified list, the following table gives the names and intended use of the lists produced by COLLATE3.
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For FIgure 43 we have moved down the fist list to see that there is indeed an 8th entry representing the lower limit of an 8th class if there were an 8th class. Of course, this is also the upper limit of the 7th class. Again, note that the index of the class is displayed in the last line of the display. | ||||||||||||||||||||
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For Figure 43 we have moved back to the top of the lists and moved to the right to see the values in the other three lists. Note here that the last item in the CMCNT list is 51, the number of items in the original list. Also, the last item in the CRFRQ list is 1 which should always be the case since the sum of all relative frequencies must be 1 representing 100% of the values. |
©Roger M. Palay
Saline, MI 48176
September, 2012