应该是前者。


The PROBF function returns the probability that an observation from an F distribution, with numerator degrees of freedom ndf, denominator degrees of freedom ddf, and noncentrality parameter nc, is less than or equal to x. The PROBF function accepts noninteger degrees of freedom parameters ndf and ddf. If the optional parameter nc is not specified or has the value 0, the value returned is from the central F distribution.

The significance level for an F test statistic is given by

p=1-probf(x,ndf,ddf);

嗯  谢谢了