distribution with /N-1/ degrees of freedom.
[note
-The quantity [alpha][space] is the maximum acceptable risk of falsely rejecting
+The quantity [alpha] is the maximum acceptable risk of falsely rejecting
the null-hypothesis. The smaller the value of [alpha] the greater the
strength of the test.
Next we'll declare the distribution object we'll need, note that
the /degrees of freedom/ parameter is the sample size less one:
- students_t dist(Sn - 1);
+ students_t dist(Sn - 1);
Most of what follows in the program is pretty printing, so let's focus
on the calculation of the interval. First we need the t-statistic,
much wider intervals, indeed such large intervals that it's hard
to be very confident in the location of the mean.
-[endsect]
+[endsect] [/section:tut_mean_intervals Calculating confidence intervals on the mean with the Students-t distribution]
[section:tut_mean_test Testing a sample mean for difference from a "true" mean]
and more data (and/or more accurate data),
is needed for a more convincing conclusion.
-[endsect]
+[endsect] [/section:tut_mean_test Testing a sample mean for difference from a "true" mean]
+
[section:tut_mean_size Estimating how large a sample size would have to become
in order to give a significant Students-t test result with a single sample test]
So in this case, many more measurements would have had to be made,
for example at the 95% level, 14 measurements in total for a two-sided test.
-[endsect]
+[endsect] [/section:tut_mean_size Estimating how large a sample size would have to become in order to give a significant Students-t test result with a single sample test]
+
[section:two_sample_students_t Comparing the means of two samples with the Students-t test]
Imagine that we have two samples, and we wish to determine whether
However, the conclusion remains the same: US cars are less fuel efficient
than Japanese models.
-[endsect]
+[endsect] [/section:two_sample_students_t Comparing the means of two samples with the Students-t test]
+
[section:paired_st Comparing two paired samples with the Student's t distribution]
Imagine that we have a before and after reading for each item in the sample:
* [link math_toolkit.stat_tut.weg.st_eg.tut_mean_size Calculate how many pairs of readings we would need
in order to obtain a significant result].
-[endsect]
+[endsect] [/section:paired_st Comparing two paired samples with the Student's t distribution]
+
-[endsect][/section:st_eg Student's t]
+[endsect] [/section:st_eg Student's t]
[/
Copyright 2006, 2012 John Maddock and Paul A. Bristow.