INSTRUCTIONS
Once the applet has finished loading, a "Compute CI" button will appear
on the screen. This may take a minute or two depending on the speed of
your internet connection and computer. Please be patient. If no begin button
appears, it is probably because your browser does not support Java 1.1.
The two-sample t statistic is used in statistical inference for comparing the means of two independent, normally distributed populations with equal variances. If sample are randomly and independently chosen, an additional assumption when working with this statistic is that the two population variances are equal. Then the degrees of freedom of sampling distribution of the two-sample t statistic is n1+n2-2. We can estimate the common value of the population variances using a statistic called the pooled variance:
Sp square = ((n1-1)s1 square + (n2-1) s2 square)/(n1 + n2 - 2)
If we can make this final assumption, then the two-sample t statistic given by
t = ((X1bar - X2bar) - (mu1 - mu2))/square root(Sp square/n1 + Sp square/n2))
Press the "Lab-value" button, choice which parent population you want "Sample from", choice how many times you want "Repeat", then "Run" the lab. You use "Repeat" button to cumulate your repeat values. You can adjust your sample size, see what will happen.