Perform an t test for the null hypothesis rr
*b=r in a classical normal regression model y=x*b+e. Under the null, the test statistic t follows a t distribution with df degrees of freedom.If r is omitted, a value of 0 is assumed.
With the optional argument string alt, the alternative of interest can be selected. If alt is
"!="or"<>", the null is tested against the two-sided alternative rr*b!=r. If alt is">", the one-sided alternative rr*b>r is used. Similarly for "<", the one-sided alternative rr*b<r is used. The default is the two-sided case.The p-value of the test is returned in pval.
If no output argument is given, the p-value of the test is displayed.