【摘要】The paper starting with the interreaction between the individual price index X and index physical volume Y,explains the formulation mechanism of the factor index of the price of the soical commodities and thing amount under the different environments where supply with the side and need side play a leading role.It reveals symbols and examines it as the feasibility of appraising the good and bad yardstick of each index.Then examining the theory frame according to the symbol thereupon,structures random varibale N1∑ni=11-Zi2 which obeys two random variables distributed B(n,p).While proving the significence level α,the value of random variable N1 makes original hypothesis H0∶E()=μ0 right under one's own states fully in three kinds H1∶(E)>μ0;E(<μ0;E()≠μ0).