We research form the quality selection of the monopoly manufacturers,and then analyze the economic relationship between the costumer which have little information and the insufficient supply of quality.

From the angle of economics, old age insurance funds are private goods with externalities, which results in insufficient supply of old age insurance funds.

In China rural credit market,the interactions between short supply and market monopoly cause the segmentation of rural credit market and the multi-equilibrium rates: relationship loan has maintained nominal zero rate while the interest rates in formal and informal credit market are determined separately.

There is a problem of shortage of quality supply in monopolistic markets because monopolists have market power.

From "Inner Conflicts of People" to "Insufficient Public Supply"——Shift of main social conflicts in Modern China;