—Table 6 here—
5.4 Reverse Causation
The cointegration results in Tables 2 (Panel C) and 4 imply that there exists a long-run relationship between population and government size. If two variables are cointegrated, one variable must Granger-cause the other or there must be Granger causality in both directions simultaneously (Engle and Granger, 1987). That is, while the panel cointegration test results show that population and government size are (Granger-causally) linked, they do not indicate the “direction” of Granger causality. So far, we have assumed – following the existing literature – that Granger causality runs from populationsize (as the independent variable) to government size (as the dependent variable). However, feedback between both variables may also exist. For instance, larger government size may correlate with higher public spending on health, education and welfare. Such increased public spending in turn may incentivize “quality” over “quantity” with respect to childbearing, thus reducing population growth at the macro-level. Conversely, increased welfare spending may also attract international migration, consequently fueling population growth. While the nature of the effect of government size on populationsize is thus a priori unclear, it is nevertheless necessary to test whether feedback exists, as such an effect would lead us to question the validity of our empirical findings.
—Table 3 here—
However, in Table 3 we also report diagnostics related to the assumptions we discussed above (cross-sectional independence, stationary residuals and slope homogeneity). First, tests of the regression residuals for unit root presence very strongly indicate that the residuals are non- stationary. 5 As discussed above, non-stationary residuals may imply a spurious regression (e.g., Kao, 1999). Second, the majority of CD-test results indicate that the residuals are affected by cross- sectional dependence. 6 As hinted at above, this may affect the validity of inference (Sarafidis and Wansbeek, 2012). Finally, we also test whether the assumption of slope homogeneity is justified. Baltagi (1981) recommends the Roy-Zellner test over the better known Chow test to examine the null hypothesis of poolability (so that populationsize has a uniform effect on government size for all countries in the sample) against the alternative that pooling is not appropriate (so that parameter heterogeneity should be allowed for). As reported in Table 3, the null of slope homogeneity of the Roy-Zellner test is always strongly rejected. 7 The incorrect assumption of slope homogeneity may yield inconsistent and potentially misleading estimates of the regression coefficients (Pesaran and Smith, 1995). In sum, the regression diagnostics strongly suggest that the results reported in Table 3 may be affected by various sources of misspecification.
This paper addresses the relationships among commuting time, transport mode, and metropolitan characteristics of elder workers in the US. Using unique information on time diaries from the American Time Use Survey for the period 2003-2018, we compute the minutes per day spent commuting, the rate of commuting done by private vehicle (car, truck, or motorcycle), active mode of transport (walking or cycling), or by public transport, and the metropolitan status of the place where workers reside, along with the populationsize of the corresponding MSA. The results suggest that elder workers in metropolitan areas commute longer times than their counterparts in non-metropolitan areas. Furthermore, there are differences across MSAs depending on the population sizes, which are estimated to be positively correlated to commuting times. Regarding transport modes, elder workers in metropolitan areas of more 2,500,000 inhabitants seem to commute more by public transport than the similar workers in less- populated or non-metropolitan areas.
general was rationally forward looking, but when the analysis was carried out separately for small and large municipalities, the rationality applied only to the small municipali- ties. According to the authors, the public sector labour unions may prevent the large municipalities from reacting optimally to changes in economic conditions. Borge and Rattsø (1993) studied the effects of populationsize on the speed of adjustment of the services structure in Norwegian municipalities. They found that large municipalities experienced stronger inertia than the smaller ones. In a further study, Borge, Rattsø and Sørensen (1995) tested the effect of political pressure groups and mass media on this sluggishness. Their findings were that the speed of adjustment was seriously affected by political pressure groups in separate municipalities. More specifically, they found that strong interest groups associated with declining sectors were able to block the adjust- ment process. Finally, in a study on the determinants of municipal labour demand in Sweden, Bergström, Dahlberg and Johansson (1998) found that the adjustment process of municipal labour demand was slower in large municipalities.
Different traditional methods exist to estimate population sizes as direct sightnings, faecal drop counts or hunting harvest which provide only relative estimates and population trends. Absolute population sizes could be yielded by a Capture-Mark-Recapture (CMR) approach. However, capturing of wild boars is difficult to realize and costly in terms of personnel and field effort. Furthermore the capture probabilities are heterogeneous due to the variable behaviour of individuals influenced by age, sex, and experience of the animals. Non-invasive genetic methods are a promising complement to the traditional methods for populationsize estimation particularly for wild boar. These methods reduce stress and capture bias and increase the number of re-captures. Faeces proved to be a suitable DNA source for wild boar genotyping, due to almost equal capture probability. However working with faeces implicates difficulties such as low DNA quality and quantity, genotyping errors as dropout and false alleles.
Ene-Margit Tiit 1
The number of residents or populationsize is important for all countries. Nowadays in many countries a series of registers have been created, which can be used for assessing the populationsize. The residency index is a tool created for estimating the under- and over-coverage of population census and calculation of proper populationsize. For this aim the concept of a sign of life – a binary variable depending on register i, person j and year k has been introduced showing if the person was active in the register in a given year. The weighted sum of signs of life indicates the probability that the person belongs to the set of residents in a given year. To improve the stability of the index a linear combination of the previous value of the index and the sum of signs of life is used. Necessary parameters were estimated using empirical data.
Wansbeek, 2012). In sum, the diagnostics reported in Table 3 indicate that the empirical results from a “traditional” approach to the population-government size nexus shown in Table 3 are likely misleading.
Table 3 also reports some “naïve” ways to remedy the misspecification issues. First, taking first- differences of both variables is expected to produce stationary variables and thus stationary residuals. Second, employing standard errors developed by Driscoll and Kraay (1998) ought to aid statistical inference, as these standard errors are not only robust to heteroskedasticity and autocorrelation, but also to general forms of cross-sectional dependence. Employing these remedies in models (5) and (6) of Table 3, we find that populationsize no longer exerts a statistically significant effect on government size, suggesting that the relationship between the two variables may indeed be spurious. However, the models in first-differences – though free of non- stationary residuals – discard valuable information about the long-run (cointegrating) relationship between population and government size. As argued above, incorrectly disregarding (panel) cointegration may be another source of misspecification and may therefore also lead to incorrect inferences (e.g., Granger, 1986, Engle and Yoo, 1987; MacDonald and Kearney, 1987).
How should one interpret the UN’s projections? It is quite likely that none of the variants will result exactly at the global level, given the divergence in trends today and the very large difference in future populationsize that relatively small differences in the average number of children make. Africa, with its high current fertility, serves as an excellent example. In the most recent UN long-range projections (performed in 1998), Africa’s population rises to a nearly stationary 2.3 billion by 2150 if women were to average 2.1 children. If, on the other hand, African couples were to show a preference for somewhat larger families in the long term, just one half child more, it would rise to 5.9 billion! Rather than judge world popula- tion prospects at the global level, one should consider the prospects for fertility decline at the regional level. One region might follow the path to the two-child family or less, while anoth- er’s show a very different trend. In the following sections, the outlook for divergent trends can be considered.
ing populationsize on the right-hand side by the S2Y W R from equation (2) shows that ∂z t ∗ /∂S2Y W R t < 0.
Concerning the dynamics of the model, an increase in the fertility rate n t of period t causes
population aging in t + 2. During this process, the rate of innovation decreases. While the model abstracts from several potentially important factors, it illustrates the main mechanism through which population aging can affect the rate of innovation. Extensions of the model could include international demand for innovative goods. However, in the empirical part, I already control for trade openness and find that it does not affect my findings. Another potential issue with the model is that it contains only one sector with R&D. In a multi- sector model, however, innovation could shift from one sector with declining demand to other sectors like health care in which demand might increase if the population becomes older. In the empirical analysis, I discuss this idea in more detail.
Our models are rooted in the microscopic description of a random (dis- crete) population of individuals characterized by one or several adaptive traits and cells characterized by their type. The population is modeled as a stochastic point process whose generator captures the probabilistic dy- namics over continuous time of birth, mutation and death for individuals and birth and death for cells. The interaction between individuals (resp. between cells) is described by a competition between individual traits (resp. between cell types). We are looking for tractable large population approxi- mations. By combining various scalings on populationsize, birth and death rates and mutation step, the single microscopic model is shown to lead to contrasting nonlinear macroscopic limits of diﬀerent nature: deterministic approximations, in the form of ordinary, integro- or partial diﬀerential equa- tions, or probabilistic ones, like stochastic partial diﬀerential equations or superprocesses.
und andere Ameisen die Futterquelle wiederfinden können. Je mehr Ameisen einem bestimmten Weg folgen, desto stärker wird die Duftspur. Je stärker die Duftspur, desto vielversprechender erscheint der Weg, so dass immer mehr Ameisen diesen Weg wählen und somit die Duftspur immer weiter verstärken. Trotzdem entscheiden sich einige vereinzelte Ameisen immer wieder in unregelmäßigen Abständen ohne erkennbaren Grund, einen anderen oder völlig neuen Weg einzuschlagen. Die Hoffnung, eine noch ergiebigere Futterquelle oder einen kürzeren, schnelleren oder einfacheren Weg zu einer bereits bekannten Futterquelle zu finden, treibt diese abweichende Handlung voran. Der Ant Colony Optimization Algorithmus ist dabei diesen letzteren, explorierenden Ameisen nachempfunden. Entgegen der Natur wird dieser Algorithmus hierbei aber sehr verkürzt. Eine Population von zufällig generierten Agenten (Ameisen) wird gestartet, die alle zufällig neue Wege erkunden. Nach einem bestimmten Zeitraum wird der Erfolg eines jeden Agenten ausgewertet. Bei einem weiteren Zyklus des Algorithmus werden Kopien der im vorherigen Zyklus erfolgreichsten Agenten generiert, die ihrerseits wieder die Gegend erkunden. Nach einigen Durchläufen kann mithilfe dieses Algorithmus eine gute Approximation für einen kürzesten Weg gefunden werden.
This study supplements the existing research in three ways. First, the selected approach – a synthesis of traditional forecasting models and statistical approaches – is innovative. Second, as far as we know, we are the first to examine tactical size rotation for the Swiss stock market. Third, we have expanded the data categories by aggregative analysts’ data supplied by IBES. This study is organised as follows. First we make a statistical descriptive analysis of the size premium in Switzerland, define the forecasting variables used in the back test and explain their selection. Then we introduce and discuss the forecasting process used. This is followed by some comments on the definition of the optimal model. Then we examine the forecast performance of our approach in various specifications and evaluate the success of tactical size strategies. We conclude the study with some thoughts about transaction costs and implementation as well as a summary.
The control variables are as expected. The individual characteristic that positively affects the probability of becoming self-employed is: if you have more education, born in Sweden, are male, have a longer tenure, more previous working places, and if your work place in 2009 ceased to exist. The only individual variable that diminishes the probability of becoming self-employed is the size of the work place. Individuals working in small establishments tend to have a higher probability of becoming self-employed. The regional control variable that increases the probability of becoming self-employed is the number of establishments in the service sector per capita. As the average establishment size increases, less individuals become self-employed. The local demand has the same effect, which is unexpected since more individuals tend to become self-employed or start new firms if the region is growing. This could be explained by the tendency to become self- employed in more rural locations where the accessibility to wage sums are lower. The regional variables that measure the age structure in the municipality are insignificant.
Z = α + β + γ + δ + θ + θ + θ + ε ,
where S is total employment in the area, f and g are functions that have to established empirically and ε is a random error term. Only levels and logarithms of the variables ED and PD were tried. A priori we expect β > 0, ∂ Z/ ∂ ED < 0 and ∂ Z/ ∂ PD > 0.
The results of the preferred specifications of this equation are given in Table 4. The equations seem well specified, have considerable explanatory power and the parameter values accord with our a priori expectations. In particular, in Great Britain, regional specialisation is seen to increase with the employment density of the region and to decrease with the population density of the region, ceteris paribus . These results support our two initial hypotheses from location theory and central place theory. At the same time, regional specialisation is also seen to increase as the size of the region falls. This finding supports our argument which suggested that the observed measures or regional specialisation will also depend in part on the size of the area chosen as a region of analysis.
Genetic studies of the Eurasian brown bear (Ursus arctos) have so far focused on populations from Europe and North America, although the largest distribution area of brown bears is in Asia. In this study, we reveal population genetic parameters for the brown bear population inhabiting the Grand Ka¸ckar Mountains (GKM) in the north east of Turkey, western Lesser Caucasus. Using both hair (N = 147) and tissue samples (N = 7) collected between 2008 and 2014, we found substantial levels of genetic variation (10 microsatellite loci). Bear samples (hair) taken from rubbing trees worked better for genotyping than those from power poles, regardless of the year collected. Genotyping also revealed that bears moved between habitat patches, despite ongoing massive habitat alterations and the creation of large water reservoirs. This population has the potential to serve as a genetic reserve for future reintroductions in the Middle East. Due to the importance of the GKM population for on-going and future conservation actions, the impacts of habitat alterations in the region ought to be minimized; e.g., by establishing green bridges or corridors over reservoirs and major roads to maintain habitat connectivity and gene flow among populations in the Lesser Caucasus.
West migrants. The empirical framework is based on a switching regression model (Goldfeld and Quandt, 1973) with endogenous switching (Maddala and Nelson, 1975; Maddala, 1983). The switching regression model can be derived from the Roy model and was first applied in the context of migration decisions by Nakosteen and Zimmer (1984). It makes it possible not only to estimate the wage differential for (prospective) migrants consistently, but also enables us to draw inferences on the selection bias of the migrant population. The remainder of the paper is structured as follows: firstly, we briefly review the findings of the empirical literature on East-West migration in Germany (Section 2). Secondly, we present an extended version of Roy’s model which considers the correlation between moving costs and abilities of individuals in the labour market. As a result, the strong predictions of Roy’s model are relaxed or even reversed (Section 3). Thirdly, we describe the data base (Section 4) and analyse the socio-economic characteristics of migrants (Section 5). Fourthly, we present the switching regression model and discuss the econometric results (Section 6). In conclusion we summarise our findings and their implications for the theory and empirics of self-selection (Section 7).
In this paper, we examine the relationship between government policies towards fertility and the change in the total fertility rate using panel data on 133 countries over the 1976- 2013 period. We use country-level data from the United Nations World Population Policies Database, and the World Bank’s World Development Indicators. 1 In our analysis we consider different types of government policy. The first is to reduce fertility through education, health care, family planning, employment programs and availability of low- cost contraception. We can refer to this as anti-fertility policy. The second is to raise fertility through a variety of government subsidies for childcare and housing, tax
8 th European Vertebrate Pest Management Conference
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In brief, the active burrow entrances are counted by walking across the field along four 100-m strips each 2.5 m wide. Hence, the entrances were counted for a total area of 1,000 m 2 . Each year, 20 to 60 fields with different crop (mostly lucerne, winter wheat and rape) were sampled and the mean index then calculated for the district. Prior to analysis, the data on autumn abundances of both species were log- transformed and then converted by differencing to series of yearly population growth rates per capita rt obtained as rt=ln Nt -N t–1. This is because we are interested in synchrony of processes rather than population numbers. Then the Pearson coefficients of correlation were calculated between 3 series of bank vole populations and one series of the common vole population.
In this paper, we use two different measures to address this issue and to gauge the quantitative importance of the effect: income per household and income per adult equiva- lent. Using the income data from the Maddison ( 2010 ) dataset for the 20th century, we show that our adjustments to the denominator lead to slower growth rates than in case of per capita incomes with the difference being roughly 1/3. The reason is that, as per capita incomes have been growing, household size has been declining. This is due to var- ious demographic changes such as declining fertility, the trend to single households, and increasing divorce rates. As a consequence, economies of scale with respect to household size have weakened over time. In our second contribution, we assess the effects of ac- counting for the size heterogeneity of households on cross-country convergence dynamics. We find that, once adjusted for household size, the pace of divergence between different countries from 1890 to around 1950 is faster, while the pace of convergence after 1950 is slower than in case of per capita incomes.
Small carry-on landers have proven to be valuable assets by avoiding additional complexity of the main satellite and transferring the risk (and cost) of close surface maneuvers entirely or at least to some extend to an independent deployable system. In order to enable the exploration and landing on medium-size airless bodies between diameters of 10 - 50 km we present in this paper the idea of advancing carry-on landers with a crushable-shell protection system to sustain higher landing velocities in the range of 1 - 5 m/s. For this, we first classified carry-on landers with respect to their touchdown and operational strategy to find similarities and identify key technologies. We evaluated the constraints of ballistic deployments for different target bodies as well as identified the niche for using simple honeycomb impact dampers compared to optional retro- propulsion systems. Further, we introduced the system design of a “guided” Shell Lander using a generic instrument carrier attached to a single ejectable crash- pad with stabilizing capability to protect the instrument carrier from structural damage, limit internal shock loads for sensitive payloads as well as reduce the amount of bounces on the surface. Finally, we presented a mission architecture for a reference case to the Martian moon Phobos as well as provided a proof of concept based on laboratory impact tests.