Modelling the reporting discrepancies in bilateral data

This paper is about the discrepancies in reported bilateral statistical data ("mirror data"). For example the trade from country A to country B is not reported the same in the two countries. The discrepancies are used to estimate the accuracy of the reporters. The estimated accuracies are to be used to compute optimal combinations of mirror data. Two models of the discrepancies are presented: (a) unbiased reporting with inaccurate reporters having a large variance, and (b) biased reporting with inaccurate reporters having a large bias (either positive or negative). Estimation methods are least squares regression and maximum likelihood. A numerical illustration is given, using data of the international trade in services. It is shown how to judge the two models empirically. For an updated�version, see CPB Discussion Paper 216 .�

The derivatives of complex characteristic roots in the econometric modelling textbook of Kuh et al.

Characteristic roots, or eigenvalues, are a useful tool in the study of linear dynamic economic models. The relation between the roots and the model coefficients are expressed in the derivatives of the former with respect to the latter. In general, the roots are complex numbers. This note discusses the derivatives of both the modulus and the cycle time of the complex roots. An important reference on this subject is Kuh et al. (1985) [hereafter: KNH]. Below it is shown that KNH discusses these derivatives unsatisfactory. In the next two sections the model and the derivatives of the roots are given. Section 4 presents the formulas for the derivatives of the modulus and the cycle time of complex roots. The substance of the paper is section 5, with a critical comment on the discussion of these derivatives in KNH. The last section gives a short conclusion. �

Continuous-time modelling in econometrics and engineering - juli 2002

This paper discusses a widely used discrete-time analog of dynamic continuous-time models. This analog can not be used for the estimation of models with fast adaption to shocks. This has been overlooked in the econometric literature. In the engineering literature this same analogon is defined, using other names and other notation. Here warnings can be found against the estimation of fast models. The engineering literature is ignored in the econometric literature.

Hourglass models of world-wide problems such as climate change

A simple model of “hourglass†problems is presented. For such problems, the benefit of a national policy measure is propagated to all countries through one single world-wide variable. The prime example is the effect of the reduction of CO 2 emission on the world climate. Five optimal solutions are given, for various situations and points of view, followed by a comparison with the outcome of permit trading.

The Elmar model: output and capacity in imperfectly competitive electricity markets

With the ongoing liberalization and integration of European energy markets and the increasing worries about security of supply, the need for thorough economic analysis of electricity markets is growing. Elmar is a model for the European electricity market, taking into account imperfect competition through conjectural variations, as well as imperfect international competition due to import capacity restrictions. The model distinguishes between competition on the output market and competition in capacity investments. We find that the least competitive of these determines wholesale prices.

The Impact of Provincial Maternity and Parental Leave Policies on Employment Rates of Women with Young Children in Canada

Maternity and parental leave policies are on the forefront of the current political agenda in Canada. This paper answers the question: does maternity and parental leave (M/PL) policy raise or lower the probability of employment for a woman? One unique feature of M/PL policy in Canada is the variation in mandated unpaid job-protected leave allowances across provinces. This variation is used in this study to identify the effect of provincial M/PL policies on employment rates of women with young children. Using the Canadian Labour Force Survey (LFS) data from 1976 to 2000, I find evidence that M/PL policy reduces the gap between the employment probabilities of women with young children versus women with older children. Moreover, a difference-in-differences model predicts a 3 to 4 percent increase in the probability of employment for women with young children (aged 0 to 2) relative to women with older children as a result of M/PL policy.

Arithmetic and geometric mean rates of return in discrete time

This memorandum presents some basic equalities and inequalities about rates of return in discrete time, without auto-correlation. The arithmetic and geometric means are discussed. Estimation of the expected payout and the median payout is discussed, including maximum likelihood estimation.

Queries with Guarded Negation (full version)

A well-established and fundamental insight in database theory is that negation (also known as complementation) tends to make queries difficult to process and difficult to reason about. Many basic problems are decidable and admit practical algorithms in the case of unions of conjunctive queries, but become difficult or even undecidable when queries are allowed to contain negation. Inspired by recent results in finite model theory, we consider a restricted form of negation, guarded negation. We introduce a fragment of SQL, called GN-SQL, as well as a fragment of Datalog with stratified negation, called GN-Datalog, that allow only guarded negation, and we show that these query languages are computationally well behaved, in terms of testing query containment, query evaluation, open-world query answering, and boundedness. GN-SQL and GN-Datalog subsume a number of well known query languages and constraint languages, such as unions of conjunctive queries, monadic Datalog, and frontier-guarded tgds. In addition, an analysis of standard benchmark workloads shows that most usage of negation in SQL in practice is guarded negation

The partition semantics of questions, syntactically

Groenendijk and Stokhof (1984, 1996; Groenendijk 1999) provide a logically attractive theory of the semantics of natural language questions, commonly referred to as the partition theory. Two central notions in this theory are entailment between questions and answerhood. For example, the question "Who is going to the party?" entails the question "Is John going to the party?", and "John is going to the party" counts as an answer to both. Groenendijk and Stokhof define these two notions in terms of partitions of a set of possible worlds. We provide a syntactic characterization of entailment between questions and answerhood . We show that answers are, in some sense, exactly those formulas that are built up from instances of the question. This result lets us compare the partition theory with other approaches to interrogation -- both linguistic analyses, such as Hamblin's and Karttunen's semantics, and computational systems, such as Prolog. Our comparison separates a notion of answerhood into three aspects: equivalence (when two questions or answers are interchangeable), atomic answers (what instances of a question count as answers), and compound answers (how answers compose).Comment: 14 page