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Plateaus in the age pattern of hazard functions at extreme ages have been discovered in large populations of medflies, Drosophila, nematodes, and people. Mueller and Rose [(1996) Proc. Natl. Acad. Sci. USA 93, 15249-15253] have proposed several age-structured demographic models to represent effects of mutation accumulation and antagonistic pleiotropy on randomly evolving schedules of demographic rates. They assert that "evolutionary theory [as embodied in their models] predicts late-life mortality plateaus." This paper defines a class of Markovian models that includes those of Mueller and Rose and obtains a characterization of the possible limiting states. For the basic model, the result implies that schedules with late-life mortality plateaus above a minimal threshold are not limiting states. The models fail, but not for reasons previously conjectured. Transient states, visited early by the process, do display mortality plateaus. Other models from this class may have a role to play in reconciling observed plateaus with evolutionary theory.

"Microsimulation, other demographic tools, and evidence of history and ethnography are used to evaluate an important 17th century household census [in Slavonia, which is modern Croatia]. Linguistic, ethnographic, and internal evidence allow adjustment of anomalies in census categories. Microsimulation based on historically and ethnographically plausible rates and household formation scenarios produces simulated households in accord with those of the adjusted census. Results permit estimation of the true population of the region, of the kinship and age composition of households under frontier conditions, and the probable future composition of households as the frontier stabilized and land shortage began to exert pressure for greater density and household complexity. Part I concentrates on historical, ethnographic, and linguistic evidence." (SUMMARY IN FRE), (excerpt)

Goldman (1978) has proposed a formula derived from stable population theory for estimating growth rates from certain counts of younger and older sisters in a population. Computer microsimulation outputs show extraordinarily large statistical errors for estimation when stable population assumptions are modified to allow for random variability such as would be encountered with field work on small populations. A derivation of Goldman's formula on more interpretable lines than that in Goldman (1978) identifies a source of variance special to this particular formula so that the large statistical errors for this example need not count in general against the feasibility of estimating demographic rates from counts of kin. [ABSTRACT FROM AUTHOR]

The performance of format demographic feedback models, like Ronald Lee's, provides a test of whether theories of endogenous fertility adjustment, like Richard Easterlin's, can explain the cyclic swings in U.S, and other births that they were designed to explain. This paper shows how the specification of a demographic feedback model determines its ability to sustain cycles of a given period and amplitude observed in data. Only a few of the many versions of Easterlinastyle theories imply formal models which do prove capable of matching U.S. targets, and then only by narrow margins. The general methods presented here are suitable for a broad investigation of the possible role of age- specific feedback in the diversity of more and less cyclic patterns in birth series in the developed world. [ABSTRACT FROM AUTHOR]

Lee's (1974) formal demographic feedback models summarize the implications for births and age-structure of neo-Malthusian theories of baby booms such as those of Easterlin. For some parameter values, such models imply sustained cycles, so-called "limit cycles", in births. Frauenthal and Swick recently reestimated a continuous-age version of Lee's basic cohort model with U.S. series and, contrary to Lee's original findings, concluded that "limit cycles oscillations have been occurring in U.S. births." This article disputes their conclusion, ascribing it to an inconsistency in detrending procedures. Furthermore, it corrects Lee's original conclusion by showing that his alternative period labor-force feedback model, estimated from U.S. series, leads to cycles of implausibly long period. This article thus reopens the question of whether any feedback model could account for the observed cycles in U.S. births. [ABSTRACT FROM AUTHOR]