Hey Chris,

I always presumed the formula was:
September_blip = Event(NewYearsEve)+mdy(9.0.0);
April_blip = Event(SummerParties)+mdy(9,0,0);

It would be interesting to compare your "Northern Hemisphere" April blip with a "Southern Hemisphere" equivalent - it may just exacerbate our September result. (Although September are our football finals...plus9 months... so does that mean NFL finals plus 9 months, etc, etc...)

Not sure how to code for fake dates in Facebook..