The 4-2-1 family structure in China: a survival analysis based on life tables.

Concern about ensuring old-age support in 4-2-1 families-consisting of four older people (paternal and maternal grandparents), two parents, and only one child-has risen with the increase in the number of families with only one child. In this article, using life table data and probability theory, we examine survival probabilities and coexistence durations for China's 4-2-1 family structure, as well as urban and rural differences and conduct a sensitivity analysis. We find that once the grandparents have all entered the "old-age" phase (over 60 years old), the probability that all four will survive is only 0.61. The four grandparents are likely to coexist for 16 years after the birth of their grandchild, then one will die and the remaining three will probably spend another 8 years together; finally, after another dies, the surviving two will coexist for another 5 years. There is no significant difference between urban and rural families in terms of the duration of their coexistence. As the ages at which the parents had their child rise, the durations become shorter. The pressure of old-age support in such families is not as severe as expected.