Unit Root Tests: Results from some recent tests applied to select Indian macroeconomic variables

Results from newly developed unit roots tests of ERS (1996), PN (1996), NP (2001) and LM (1994) are compared against their traditional counterparts (ADF, PP and KPSS) on select Indian macroeconomic data. Results from ERS, PN and NP are broadly in agreement. However, using the general to specific criterion of Hall (1994) and the Modified Information Criterion (MIC) of NP for lag length selection, it is found that different lag length can lead to different results. Furthermore, results from using these criteria are also sensitive to the maximum lag length. Both KPSS and its modified version, LM, are found to be prohibitively sensitive to the lag length used. Since as of now no theoretical criterion exists for lag length selection for tests which test the null of stationarity, their use should be avoided, even for the purpose of so-called ‘confirmation’. Another important finding is that frequency of the data and span covered by the sample size plays an important role and whenever feasible, tests must be conducted with as many different frequencies as the availability of data permits. It is not only a large sample size that is important, but also the span covered, an issue raised long ago by Campbell and Perron (1991).

Using Subjective Income Expectations to Test for Excess Sensitivity of Consumption to Predicted Income Growth

We test for precautionary saving and excess sensitivity of consumption to predicted income growth using a 1989-93 panel survey of Italian households that has measures of subjective income and inflation expectations. These expectations provide a powerful instrument for predicting income growth. The empirical specification controls for predictable changes in labor supply and allows a fairly general specification for the stochastic structure of the forecast error. We find that consumption growth is positively correlated with the expected variance of income and uncorrelated with predicted income growth. Overall, the results support the precautionary saving modelSubjective expectations, precautionary saving, excess sensitivity

Debt Revolvers for Self Control

By 1998, about two-thirds of U.S. households held a bank-type credit card. Despite high interest rates, most revolve credit card debt. The majority of debt revolvers have substantial liquid assets, apparently violating arbitrage. We propose an "accountant-shopper" model that could provide an explanation for this puzzle. In our model, the "accountant self" (or spouse) of the household can control the expenditures of the "shopper self" (or spouse) by limiting the purchases the shopper can make before encountering the credit limit. Since the card balance is used for control purposes, the accountant self may also find it optimal to save in lower-return riskless assets. Using attitudinal responses and demographic data from the pooled 1995 and 1998 Surveys of Consumer Finances, we estimate a bivariate probit model of the decisions to have a credit card and to revolve debt on it, allowing for sample selection. The pattern of estimated coefficients is consistent with debt revolvers being motivated primarily by self-control considerations rather than intertemporal consumption smoothing.credit cards, consumer debt, portfolio puzzles, household portfolios

Using formal methods to support testing

Formal methods and testing are two important approaches that assist in the development of high quality software. While traditionally these approaches have been seen as rivals, in recent years a new consensus has developed in which they are seen as complementary. This article reviews the state of the art regarding ways in which the presence of a formal specification can be used to assist testing

The welfare effects of inflation: a cost-benefit perspective

This paper reviews theory and evidence of the welfare effects of inflation from a costbenefit perspective. Basic models and selected empirical results are discussed. Historically, in assessing the welfare effects of inflation, the distortion of money demand played a prominent role. More recently, interactions of inflation and taxation came into focus. Growth effects of inflation as well as welfare effects of unanticipated inflation and of inflation uncertainty are also addressed. To assess the policy question whether inflation should be reduced or eliminated, the costs of disinflation play a role. Finally, the trade-off between the benefits of reducing inflation and the costs of disinflation is discussed and an overall assessment of the net welfare effects of achieving price stability is provided. --Inflation,price stability,welfare costs and benefits,distortions,money demand,consumption allocation,tax-inflation interaction

"Fiscal Deficit, Capital Formation, and Crowding Out in India: Evidence from an Asymmetric VAR Model"

This paper analyzes the real (direct) and financial crowding out in India between 1970–71 and 2002–03. Using an asymmetric vector autoregressive (VAR) model, the paper finds no real crowding out between public and private investment; rather, complementarity is observed between the two. The dynamics of financial crowding out is captured through the dual transmission mechanism via the real rate of interest—that is, whether private capital formation is interest-rate sensitive and, in turn, whether the rise in the real rate of interest is induced by a fiscal deficit. The study found empirical evidence for the former but not the latter, supporting the conclusion that there is no financial crowding out in India. The differential impacts of public infrastructure and noninfrastruture innovations on the private corporate sector are carried out separately to analyze the nonhomogeneity aspects of public investment. The results of the Impulse Response Function reinforced that no other macrovariables, including cost and quantity of credit and the output gap, have been as significant as public investment—in particular, public infrastructure investment—in determining private corporate investment in the medium and long terms, which has crucial policy implications.

Digital implementation of the cellular sensor-computers

Two different kinds of cellular sensor-processor architectures are used nowadays in various applications. The first is the traditional sensor-processor architecture, where the sensor and the processor arrays are mapped into each other. The second is the foveal architecture, in which a small active fovea is navigating in a large sensor array. This second architecture is introduced and compared here. Both of these architectures can be implemented with analog and digital processor arrays. The efficiency of the different implementation types, depending on the used CMOS technology, is analyzed. It turned out, that the finer the technology is, the better to use digital implementation rather than analog