# To calculate cross elasticity of demand, does percentage change in quantity demanded have to be market demand instead of individual demand? [closed]

If I try to calculate cross elasticity of demand (XED or CED) with individual demand quantity, it seems to break down since even small increase when the base number is small is a big increase in percentage. e.g. 1 to 2 is a 100% change.

## closed as unclear what you're asking by Giskard, ml0105, Wecon, Jamzy, EnergyNumbersJul 19 '16 at 16:02

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$XED=\frac{\Delta q_i}{q_i}\cdot \frac{p_j}{\Delta p_j}$
It is right that in your case $\frac{\Delta q_i}{q_i}=\frac{2-1}{1}=1$