ラスパイレス・パーシェ・フィッシャー指数

\( \normalsize p_{c,t}\ :\ the\ price\ of\ c\ in\ period\ {\bf t} \\ \normalsize q_{c,t}\ :\ the\ quantity\ of\ c\ sold\ in\ period\ {\bf t} \\ P_{L}\ =\ \frac{\large\sum (p_{c,t_{n}} \cdot q_{c,t_{0}} )}{\large\sum ( p_{c,t_{0}} \cdot q_{c,t_{0}} )}\ \times\ 100 \\ P_{P}\ =\ \frac{\large\sum (p_{c,t_{n}} \cdot q_{c,t_{n}} )}{\large\sum ( p_{c,t_{0}} \cdot q_{c,t_{n}} )}\ \times\ 100 \\ P_{F}\ =\ \sqrt{P_{L}\cdot P_{P}} \)