I think the difference in this case is that we are looking at a point that exceeds the current series maximum. If we had a single value from a series without a trend, we would expect it to fall below the maximum value observed so far (perhaps after sampling at least 2 points - I will think about that later), and so I reckon that the likelihood of a positive trend will be higher than for a zero or negative trend because of that fact.<p>I may try and actually work it out to see if what I&#x27;m saying is correct, but one thing I <i>can</i> tell you that likelihood of me not doing so is greater ;-).