Mean, median, mode, first quartile, third quartile; all these are parts of the measures of central tendency. Some of these are easy to find no matter how many data pieces there are, others are much more difficult, even with only a few. Thankfully, we have graphing calculators, which us to find these much more easily.
Below are the directions for finding these five, and others, using a TI-83 or TI-84:
1. To begin, press “Stat,” followed by “Enter.” This will activate the “Edit…” option.
2. Fill in the list underneath the heading, “L1.” Use all the data points, in any order, as it does not matter for this purpose. If there are already numbers in the list, arrow up until the “L1” is highlighted, then press “Clear.” Arrow down once, and proceed as normal.
3. To find the measures of central tendency, press “Stat,” “Right Arrow,” then “Enter.” This will be “1-Var Stats,” under the “Calc” menu. Press “Enter” again. All the outputs will be displayed on two screens. Arrow up and down to see all of them.
4. Read what the symbols represent:
-The X with the bar over it is the mean.
-Sigma X is the sum of all the data points.
-Sigma X squared is the sum of the squares of all the data points.
-Sx is the variance.
-Lowercase sigma x is the Standard Deviation.
-n is the number of data points.
-MinX is the minimum value.
-Q1 is the first quartile
-Med is the median
-Q3 is the third quartile
-MaxX is the maximum value.
The only thing that does not appear here is the Mode. That must be found manually, though that tends to be the easiest piece to find.
5. Trouble Shooting: When the list does not clear by normal means, press “Stat,” “4,” “Enter.” This should clear the list. If it does not, try resetting the calculator. WARNING: This will clear all stored data including programs and applications which are not part of the default setting. This should only be used when all else fails, or if there is nothing on the calculator worth saving. To do so, press “2nd,” “+,” “7,” “Enter,” “2.”
