Improved forecasting with leading indicators: the principal covariate index

We propose a new method of leading index construction that combines the need for data compression with the objective of forecasting. This so-called principal covariate index is constructed to forecast growth rates of the Composite CoincidentIndex. The forecast performance is compared with an alternative index based on principal components and with the Composite Leading Index of the Conference Board. The results show that the new index, which takes the forecast objective explicitly into account, provides significant gains over other single-index methods, both in terms of forecast accuracy and in terms of predicting recession probabilities.business cycles;turning points;index construction;principal covariate;principal component;time series forecasting

Prediction beyond the survey sample: correcting for survey effects on consumer decisions.

Direct extrapolation of survey results on purchase intentions may give a biased view onactual consumer behavior. This is because the purchase intentions of consumers maybe affected by the survey itself. On the positive side, such effects can be incorporated ineconometric models to get reliable estimates of actual behavior of non-surveyed consumers,which often is the ultimate purpose of survey studies. This paper proposes a reasonablysimple methodology to correct for such possible survey effects and to get consistent pre-dictions beyond the survey sample. The potential merits of the method are illustrated bya supermarket survey on easy-to-prepare food products and related health issues. Thisindicates that the required corrections can be quite substantial and that predictions thatneglect survey effects can be seriously biased indeed.econometric models;consumer behavior;bias correction;purchase prediction;survey effects

Estimated Parameters Do Not Get the "Wrong Sign" Due To Collinearity Across Included Variables

Estimation results in linear regression models are sometimes in contrast with what was expected on the basis of a certain set of hypotheses or theory, in the sense that one or more parameters have the "wrong sign". One could be inclined to think that this is due to collinearity across explanatory variables, suggesting one should leave out one or more of the collinear variables. In this note we show that this is not a valid approach. Additionally, we show that "wrong signs" can occur because of correlations between included and omitted variables, so that "wrong signs" may occur if the model is not correctly specified. That is, if we find 'wrong signs" we should start questioning our model choice, not the data.parameter estimation;collinearity;misspecification

Immigrant gender convergence in education and on the labor market

Immigration tends to have a mitigating effect on the socioeconomic gender gap among immigrants. To explain this finding, we propose a gender convergence hypothesis that states that migration to a modern ‘open’ society offers women the opportunity to improve their position relative to that of men. In such a society, there are (almost) equal chances to participate in education and paid labor. The equalizing effect will be larger if the immigrants come from less developed regions, since women then have more room to improve their position. However, there may also be countervailing cultural powers within the immigrant group. The gender convergence hypothesis proposed here is tested for immigrants in the Netherlands. Using survey data, we investigate the educational and labor market position of Turkish, Moroccan, Surinamese, and Antillean males and females. We find convergent trends, particularly among Moroccan immigrants who come from less developed regions in their country of origin and who meet less cultural in-group barriers than, for example, Turkish immigrants.

Correcting for Survey Effects in Pre-election Polls

Pre-election polls can suffer from survey effects. For example, surveyed individuals can become more aware of the upcoming election so that they become more inclined to vote. These effects may depend on factors like political orientation and prior intention to vote, and this may cause biases in forecasts of election outcomes. We advocate a simple methodology to estimate the magnitude of these survey effects, which can be taken into account when translating future poll results into predicted election outcomes. The survey effects are estimated by collecting survey data both before and after the election. We illustrate our method by means of a field study with data concerning the 2009 European Parliament elections in the Netherlands. Our study provides empirical evidence of significant positive survey effects with respect to voter participation, especially for individuals with low intention to vote. For our data, the overall survey effect on party shares is small. This effect can be more substantial for less balanced survey samples, for example, if political orientation and voting intention are correlated in the sample. We conclude that pre-election polls that do not correct for survey effects will overestimate voter turnout and will have biased party shares.data collection;bias correction;survey effects;intention modification;pre-election polls;turnout forecast;self-prophecy

Transconductor and integrator circuits for integrated bipolar video frequency filters

A description is presented of novel transconductor and integrator circuits which can be used in integrated video frequency filters in bipolar technology. The transconductor consists of a parallel connection of a passive nominal transconductance and an active variable transconductance, resulting in good high-frequency performance up to 70 MHz and less than 1% linearity error for input signals up to 2V pp. The integrator incorporates an operation transconductance amplifier circuit which provides a tunable integrator phase. Simulation results for all circuits and for a fifth-order elliptic low-pass filter with a nominal cutoff frequency of 5 MHz are presente

Practical formulation of the relation between filter specifications and the requirements for integrator circuits

The design of integrated, high-frequency, continuous-time filters has made considerable progress in the past few years. As the signal frequencies increase the design of the integrator circuits used in most of these filters becomes more critical. To give direction to the circuit design, minimum specifications for the gain and phase of the integrator circuits would be helpful. A practical method for obtaining these integrator specifications from the filter specifications is developed. The method is applied to a sixth-order Chebyshev band-pass filter, and the result is verified by computer simulatio

A single-electron inverter

A single-electron inverter was fabricated that switches from a high output to a low output when a fraction of an electron is added to the input. For the proper operation of the inverter, the two single-electron transistors that make up the inverter must exhibit voltage gain. Voltage gain was achieved by fabricating a combination of parallel-plate gate capacitors and small tunnel junctions in a two-layer circuit. Voltage gain of 2.6 was attained at 25 mK and remained larger than one for temperatures up to 140 mK. The temperature dependence of the gain agrees with the orthodox theory of single-electron tunneling.Comment: 3 pages, 4 figures (1 color), to be published in Appl. Phys. Let

Estimated Incident Cost Savings in Shipping Due to Inspections

The effectiveness of safety inspections has been analysed from various angles, but until now, relatively little attention has been given to translate risk reduction into incident cost savings. This paper quantifies estimated cost savings based on port state control inspections and industry vetting inspections. It is based on a unique dataset of 515,194 ship arrivals and inspections from the United States of America and Australia, and inspections of three industry vetting inspection regimes, for the time period 2002 to 2007. The risk reducing effect of inspections is estimated by means of duration models, in terms of inspection gains based on the probability of survival. The results suggest average total estimated cost savings in the range of USD 74 to 192 thousand (median USD 19 to 46 thousand) owing to reduced risk of total loss due to a port state control inspection. Cost savings for industry inspections are found to be even higher, especially for tankers. The savings vary by type, age and size of the ship. The benefits of an inspection are in general larger for older and larger vessels, and also for vessels with undefined flags and unknown classification societies. As inspection costs are relatively low in comparison to potential cost savings, the results underline the importance in determining high risk ships to prevent costs due to total loss of ships.maritime safety;duration analysis;ship inspection

Accurate automatic tuning circuit for bipolar integrated filters

An accurate automatic tuning circuit for tuning the cutoff frequency and Q-factor of high-frequency bipolar filters is presented. The circuit is based on a voltage controlled quadrature oscillator (VCO). The frequency and the RMS (root mean square) amplitude of the oscillator output signal are locked to the frequency and the RMS amplitude of a reference signal, respectively. Special attention is paid to the actual Q-factor in the oscillator. Experimental results for a breadboard circuit operating from 136 to 317 kHz are presente