need helping determing what normal variance is

[alphatmw]

in about a 3 hour session today, i went up 2 1/2 buy ins, then dropped about 4 buy ins.

then i started another session about 2 hours ago and i'm up 4 buy ins.

is this normal variance or greater than what should be normal? i play 4 tables at a time on the .1/.25 NL.

about half of the downstreak was stupid play on my part and about half was bad beats. still, variations of half my bankroll ($200) seem like a lot.