On a relationship between conception rates in a fertility model
Singh, V.K.; Singh, U.N.
Janasamkhya 5(1): 61-67
1987
PMID: 12281215 Document Number: 356335
Assuming a functional relationship between conception rates, amodel for 1st birth intervals was derived and empirically verified. The simple exponential function for conception rate, which was used to derive a probability model for 1st birth interval, permits the model to have no more than 5 parameters and takes into account the declining trend along conceptions. The model also can be applied to a situation where early married life of the female is affected by social factors. The proposed model was applied to observed data with a view toward estimating the fecundability and at the same time observing the model's validity. A table presents a distribution of time of 1st live birth conception measured in months for females married at or after age 16 and with a marital duration of 10 years or longer. The data were taken from Chakrabarty (1976), which were reproduced in Singh and Singh (1982). The data collected for the "Demographic Survey of Varanasi (Rural), 1969-70" relate to a rural part of India. The mean and variance of the observed distribution were 2.7565 years and 6.0515 years, respectively. As fecundability changes over parity or conception, this fact should be given due consideration in fertility models.