Two Sample T stats in StatCrunch Video Lecture | Statcrunch Tutorials for Beginners - Data & Analytics

hello my name is Webster West and I'm
the developer statcrunch this is a quick
tutorial on how to do a two sample T
hypothesis test and a two sample T
confidence interval using statcrunch the
data segments are used in this tutorial
contains a variety of information for a
sample of four-bedroom homes listed for
sale in the Bryan College Station Texas
area I collected this data set in
December of 2008 the two columns I want
to focus on the data set are the square
footage column and the location column
you'll notice we have 15 homes listed
for sale in Bryan Texas in our sample
and 15 homes in our sample listed for
sale in College Station Texas the
question I want to address in this
tutorial is can we determine if there's
a difference between the average square
footage a four-bedroom homes listed for
sale in Bryan Texas and the average
square footage of 4 bedroom homes listed
for sale in College Station Texas so we
want to compare the average square
footage across these two locations to do
so I'll go to the stat menu and choose t
statistics to sample with data we'd use
the width summary option if we had
sample means and sample standard
deviations for both of them locations
but in this case we have there oo data
let's choose the first sample here as
being in the square footage column and
that sample is going to be defined where
location is College Station Texas
sample2 who is also on the
square-footage column and its location
will be in Bryan Texas okay so most
samples are in the square footage column
the first samples defined where location
is College Station the second samples
define where location is Bryan Texas we
could choose whether or not to pool the
variances here by unchecking this option
or checking this option I'll leave it on
for now if we click Next we see that the
hypothesis test option is on by default
in this case the null mean difference
between the two average square footages
across the locations would be zero so
the default values what we would want to
use in this case the alternative here we
want to know if there's a significant
difference we haven't specified a
direction so the alternative would be
not equal in this case clicking
calculate we get our output here we want
to focus on the p-value here zero point
seven five seven one a very large
p-value certainly larger than any
standard level of significance that one
might use 2005 or 0.01 so in this case
we would fail to reject the null
hypothesis so there's no difference in
this case no significant difference
between the two average square footages
now if we wanted to do a confidence
interval in this case we'd go the
options menu choose edit turn on the
confidence interval option the default
level of zero point nine five will give
you a 95% confidence interval let's
click on calculate here
so in this case the 95% confidence
interval for the difference between the
two average square footages across the
locations the lower limit is negative
692 roughly and the upper limit is 509
so you'll see that zero sits right in
this interval so it's among the range of
likely values for the difference between
the two average square footages across
the locations so once again we would
conclude here that there's no difference
between the average square footages a
four-bedroom homes in bryan and the
average square footage of four-bedroom
homes and College Station at least among
those that are listed for sale that's it
for the tutorial I hope you find it
useful