Variance can be observed and measured as it refers to probabilities of certain hands making the best hand on the river, Luck cannot be measured as it is just that, Not skill but just pure luck.
I have had days when I could not lose, and have spent 8 or more hours playing SnGs getting into the money in every game, other days I could not win a Sausage, I do not put it down to Luck or the lack of it, it is all down to the Variance of the game.
As Einstein once said for every action, there is an opposite and equal reaction, same goes for Poker some days you are on top of your game and everything falls into place, other days you do badly because you make more mistakes,
A few weeks ago I played 8 of the possible 9 Free-rolls on
pokerstars, I made the money 7 times, The final table in 3 of the games, and won one outright. The following week playing the same games, I barely made the money once.
What changed? The game was the same, I am still the same player, The only thing to change was the Variance of being dealt the right hands, at the right time, and playing them in the right way, It is all part of playing Poker, You cannot expect to win all the time, it just does not happen.
Just ask Phil Helmut! I love watching him blow his top in some games.
When the fun Stops, STOP!