from Dr. Sakamoto's lecture (Oct 4)
Y=a+bX+cW+dXW
Where
Y= your degree of angry
X= boyfriend forgot your B'day --> probably not that matter, sometimes he forgot
W= boyfriend had a dinner with his ex-girlfriend --> just a dinner, not a big deal
XW= boyfriend forgot your B'day and he had a dinner with ex ON THAT DAY!!
Lets imagine how big, oh lets use "significant", the effect of interaction term will be!
