Fluctuations
How complete is the mean as a statistic of ensemble behavior?
 Are there many members of the ensemble that have properties that deviate substantially from the mean?
 Look at the standard deviation s


 This relates to the heat capacity

 Relative to mean is the important measure


Fluctuations vanish in thermodynamic limit N??
Similar measures apply in other ensembles
 volume fluctuations in NPT; moleculenumber fluctuations in mVT
Click here for an applet illustrating fluctuations