Tests for Structural Changes in Time Series of Counts

We propose methods for detecting structural changes in time series with discrete‐valued observations. The detector statistics come in familiar L2‐type formulations incorporating the empirical probability generating function. Special emphasis is given to the popular models of integer autoregression and Poisson autoregression. For both models, we study mainly structural changes due to a change in distribution, but we also comment for the classical problem of parameter change. The asymptotic properties of the proposed test statistics are studied under the null hypothesis as well as under alternatives. A Monte Carlo power study on bootstrap versions of the new methods is also included along with a real data example.     

Fourier–type tests involving martingale difference processes

We develop testing procedures which detect if the observed time series is a martingale difference sequence. Furthermore, tests are developed that detect change–points in the conditional expectation of the series given its past. The test statistics are formulated following the approach of Fourier–type conditional expectations first proposed by Bierens (1982 Bierens, H. J. (1982). Consistent model speci?cation tests. J. Econometr. 20:105–134.[Crossref], [Web of Science ®] , [Google Scholar]) and have the advantage of computational simplicity. The limit behavior of the test statistics is investigated under the null hypothesis as well as under alternatives. Since the asymptotic null distribution contains unknown parameters, a bootstrap procedure is proposed in order to actually perform the test. The performance of the bootstrap version of the test is compared in finite samples with other methods for the same problem. A real–data application is also included.     

Prediction of posttraumatic stress disorder symptomatology after childbirth – A Croatian longitudinal study

Background

Following childbirth, a vast number of women experience some degree of mood swings, while some experience symptoms of postpartum posttraumatic stress disorder.

The limited effect of increasing educational attainment on childlessness trends in twentieth-century Europe,women born 1916–65

During the twentieth century, trends in childlessness varied strongly across European countries while educational attainment grew continuously across them. Using census and large-scale survey data from 13 European countries, we investigated the relationship between these two factors among women born between 1916 and 1965. Up to the 1940 birth cohort, the share of women childless at age 40+ decreased universally. Afterwards, the trends diverged across countries. The results suggest that the overall trends were related mainly to changing rates of childlessness within educational groups and only marginally to changes in the educational composition of the population. Over time, childlessness levels of the medium-educated and high-educated became closer to those of the low-educated, but the difference in level between the two better educated groups remained stable in Western and Southern Europe and increased slightly in the East.     

Punks,Goths, and Other Eye‐Catching Peer Crowds: Do They Fulfill a Function for Shy Youths?

Adolescent peer crowds such as Punks and Goths are mainly identified by their strikingly unusual or even shocking appearances. Although many studies find these crowds, few have tried to explain why some youths take on these startling or shocking appearances. We hypothesized that an off‐putting appearance is a way to cope with behavioral inhibition by limiting social contacts. Using data from 1,200 7th–11th graders, we compared peer crowds characterized by their startling appearance (“Radical” crowds) with three theoretically relevant comparison groups. Results showed that youths affiliating with Radical crowds were more inhibited than other youths, including those in crowds previously shown to be shy or socially anxious. Inhibited Radicals, however, had poorer emotional adjustment than inhibited youths in other crowds. If Radical styles are a way for inhibited youths to cope by limiting social contacts, the strategy does not seem to be beneficial for emotional adjustment.     

Stochastic Bounds with a Low Rank Decomposition

We investigate how we can bound a discrete time Markov chain (DTMC) by a stochastic matrix with a low rank decomposition. In the first part of the article, we show the links with previous results for matrices with a decomposition of size 1 or 2. Then we show how the complexity of the analysis for steady-state and transient distributions can be simplified when we take into account the decomposition. Finally, we show how we can obtain a monotone stochastic upper bound with a low rank decomposition.     

Robust confirmatory factor analysis based on the forward search algorithm

A key concept of the forward search algorithm in confirmatory factor analysis is ordering of the data on the basis of observational residuals. These residuals are computed under the proposed model and measure the discrepancy between the observed and predicted response for each unit of the sample. Regression-type factor scores are used to estimate model predictions. Informative forward plots are created for indexing influential observations and to show the dynamics of the estimates throughout the search. The detailed influence of each observation on the model parameters and fit indices is analyzed and a robust model inference is achieved. Real and simulated data sets with known contamination schemes are used to demonstrate the performance of the forward search algorithm.     

Fertility Decline in Czechoslovakia During the Last Two Centuries

The decline of fertility in Czechoslovakia on the territory of the Czech Socialist Republic began with a rise in the age at marriage; the decline of marital fertility began only after 1860. On the territory of the Slovak Socialist Republic marital fertility began to decline after 1900 without previous significant changes in the age at marriage. The differences between the demographic behaviour in the two parts of Czechoslovakia have persisted, although they are now gradually disappearing. There are other significant regional differences in the fertility decline caused by the overall process of economic and social development. The end of the demographic transition in the Czech Socialist Republic came during the 1930's and in the Slovak Socialist Republic during the 1960's.