=T.TEST(array1, array2, tails, type)
is a set of numerical values or cell references. We will place our sample data in this
is a set of numerical values or cell references. We have only one set of data, so we will
use the historical mean, 6.7, as the second data set. To do this, we create a column with each
entry equal to 6.7.
is the number of tails for the distribution. It can be either 1 or 2. Now that we are
performing a one-sided test, we will enter a 1 instead of a 2.
can be 1, 2, or 3. Type 1 is a paired test and is used when the same group is tested twice
to provide paired “before and after” data for each member of the group. Type 2 is an unpaired
test in which the samples are assumed to have equal variances. Type 3 is an unpaired test in
which the samples are assumed to have unequal variances. The variances of the two columns
are clearly different in our case, so we use type 3. There are ways to test whether variances are
equal, but when in doubt, use type 3.
Alternative Excel Functions
T.TEST replaces the function:
=TTEST(array1, array2, tails, type)
Throughout the course we will provide alternative functions that existed prior to Excel 2010 that can
still be used in Excel 2010.
3.2.6 – Comparing two populations
So far, we have conducted
hypothesis tests, collecting a sample from one
population and testing to see if its average was significantly different from the historical average.