Showing papers on "Tobit model published in 1995"

Life Cycle Productivity in Academic Research: Evidence from Cumulative Publication Histories of Academic Economists

Abstract: Casual observation suggests that the temporal pattern of productivity varies dramatically across individuals, particularly in risky endeavors such as a research career in academia. Some individuals remain productive researchers throughout their career. Others who show early promise become deadwood before their time. Some authors produce papers like a well oiled machine, while others publish at a highly erratic rate. Opposing this is a widely held view that there is a common life-cycle component underlying individual productivity. The aging process itself is thought to lead to the initial rise and eventual decline of creative productivity. In addition, human capital models typically imply that investment in skills will decline with age [7]. Both of these ideas suggest that output will be hump-shaped over the life cycle. Econometric studies of life cycle productivity have addressed this with regressions which are quadratic functions of age or experience [1; 5]. The quadratic conveniently delivers the sought after hump-shaped pattern in productivity. There are conceptual problems with the quadratic however. It implies a symmetric output path centered on its peak, which is inappropriate if productivity peaks early in the career but remains significant thereafter. In addition, data on publishing productivity is heavily affected by the "zeros problem:" the most common number of publications for an active professor in any given year is zero. This requires an estimation procedure designed to accommodate a high probability mass at zero. Levin and Stephan [5] address this problem with the tobit regression. The tobit is a truncated regression model, where in this context publications are distributed as a truncated normal random variable if a vector combination of attributes and coefficients exceeds a threshold level, and are zero other-

"The rich are just like us, only richer." Poverty functions or consumption functions? Evidence from Uganda

Abstract: The concept of a poverty function is introduced, modelling the shortfall of household consumption from the poverty line as a function of reduced form determinants such as human capital and land holdings. The model is estimated using a tobit and data from Uganda. Parameters from the model are found to be similar to those from consumption functions, indicating that the poor receive comparable rates of return on their assets to the non-poor. Education of both men and women appears to raise the welfare of the poor as well as the non-poor, in both urban and rural areas.

Isolating the Determinants of Innovativeness: A Split-Population Tobit (SPOT) Duration Model of Timing and Volume of First and Repeat Purchase:

Abstract: The authors present the Split-Population Tobit (SPOT) duration model to incorporate two conceptually distinct dimensions of innovativeness in a single framework, namely, the timing and volume of adoption. Rather than utilizing a diffusion model specification based on word-of-mouth and social contagion effects, the present approach uses a growth model specification and delineates a general function of time to describe the distribution of adoption timing. Estimation and several validation exercises performed on a data set describing the diffusion of personal computers across a sample of over 3000 U.S. firms provide strong support for the superiority of the SPOT model over models derived from restricted conceptualizations of innovativeness. The empirical work, albeit modest, tests the impact of covariates, such as firm-size and decision-centralization, on the dimensions of innovativeness and sheds light on some inconsistent findings in the innovation adoption literature. The authors subsequently derive the e...

Willingness to Pay for Public Television and the Advent of "Look-Alike" Cable Television Channels: A Case Study

Abstract: In this case study we examine willingness to pay (WTP) for PBS using an open-ended, single-question contingent valuation method. Using data collected from 128 mail and 101 telephone surveys, we develop illustrative findings with respect to 'look-alike' cable television on WTP for PBS. Inverse demand equations were estimated. Statistically significant effects were found in models estimated with both biased and adjusted data using ordinary least squares, restricted least squares, and Tobit censored regression methods.

Are U.S. Nontariff Barriers Retaliatory? An Application of Extreme Bounds Analysis in the Tobit Model

Abstract: The extreme bounds analysis in Leamer (1982) is extended to the Tobit model with censoring. The extension involves the simple modification of replacing the censored values of the dependent variable by their expectation conditional on the MLEs and using the negative of the Hessian evaluated at the MLEs in place of the inverse of the covariance matrix. The application of this method to a data set that pools U.S. nontariff barriers across industries and countries arrives at the surprisingly robust (to changes in the prior) conclusion that U.S. nontariff barriers against its largest trading partners are already significantly retaliatory. Copyright 1995 by MIT Press.

Rationing, mortgage demand and the impact of financial deregulation

Abstract: The paper uses Family Expenditure Survey data to estimate a reduced form, cross-section model, of mortgage demand. A double hurdle model is estimated which takes account of potential mortgage rationing. The model contrasts with the usual limited dependent variable model (Tobit) where zero values for purchases are observed and treated as equilibrium observations. The empirical specification allows for the deregulation of financial services in the 1980s, and tests for the impact of this on mortgage demand. The null hypothesis that capital markets are perfect and that rationing was not a binding constraint over the sample under study was rejected. The research seeks to better understand the impact of credit rationing upon household behavior. Copyright 1995 by Blackwell Publishing Ltd

Factors affecting commercial bank lending to agriculture

Abstract: A tobit econometric procedure was used to examine the effect of selected demand and supply factors on nonreal estate agricultural lending by commercial banks in Texas. Results show that banks have reduced their agricultural loan portfolios in response to increased use of interest sensitive deposits after deregulation, Moreover, almost half of this decrease came from banks that stopped making agricultural loans. Also, results show that banks affiliated with multi-bank holding companies lend less money to agriculture relative to their assets than do independent banks.

Foreign-owned Firms' Campaign Contributions in the United States: An Exploratory Study

Abstract: This study extends previous empirical work on corporate political activity by examining which foreign-owned firms provide campaign contributions to United States legislators. While numerous studies have examined which domestic firms make campaign contributions, little is known about the propensity of foreign-owned firms to make contributions. Using logit and Tobit analyses, the findings suggest that firm size, legislative issues, foreign ownership, and cultural characteristics are important determinants of a foreign-owned firm's political strategy. The findings also suggest that there are strong parallels between the political strategies of foreign-owned firms and domestic firms.

Recent contributions to censored regression models

Abstract: A brief survey of estimation of parameters in a censored regression model (known as the Tobit model) and some details of the properties of LAD (least absolute deviation) estimates and tests of significance of linear hypotheses are given.

An empirical analysis of participation in US government farm programmes

Abstract: Factors affecting the participation of individual Kansas farms in government programmes are considered. A sample drawn from over 1600 Kansas farms for nine years is used in the context of a simultaneous equation Tobit regression to investigate the effects of various factors on the probability and expected level of participation in farm programmes. The results suggest that differences in farm sizes, incomes, types and farming practices influence participation in government programmes. Small, sole-proprietor, livestock operations with low debt levels receive the lowest levels of support. Conversely, large corporate crop farms receive the highest levels of government support.

Economic Adjustments of Households on Entry Into Retirement

Abstract: This study focuses on economic adjustment to a major life-cycle turning point, the entry into full retirement, and its immediate impact on income and spending patterns. Cross-sectional data from the Bureau of Labor Statistics Consumer Expenditure Survey interview tapes are analyzed for 1984-1987. Tobit regression analysis of socioeconomic variables on 31 expenditure categories reveals significant increased proclivities to spend on transportation, health, entertainment, and trips immediately after retirement. Older retirees spend less than do younger retirees for all expenditure categories except health insurance and gifts. Singlefemales suffer the most substantial decline in postretirement income, but this is not offset by concurrent expenditure decreases. This unsustainable dissaving rate after retirement poses a severe problem for single women.

Labour Supply of Married Women in Poland A Microeconometric Study Based on the Polish Labour Force Survey

Abstract: ZEW Discussion Paper No.95-12, Mannheim#### not available in German The labour supply of married women in Poland is studied using the Polish Labour Force Survey on three econometric models, viz. Tobit, Three Regime Tobit and Heckit. It is shown that the choice of model has an influence on conclusions drawn. In particular, the Tobit model - which has been widely applied in empirical labour supply analysis - turns out to be a strikingly bad predictor. Further, there is disagreement between the models regarding the wage elasticity of hours supplied. The preferred model for predicting hours of work is the Heckit model. This shows that an increase in the wage rate will induce employees to reduce their number of hours worked. Download Volltext: (pdf, 208 kb)

Explanation of Off-farm Work Participation in Rural Pakistan

Abstract: The role of off-farm employment in augmenting household farm income in the developing countries is of special significance, given the land and water resource constraints and the alarming, rate of population growth This study focuses on the rural household in Pakistan in an effort to understand the economic and social factors that affect off-farm work participation of male household members in the rural areas The data are derived from the cross-section survey carried out by the International Food Policy Research Institute for the year 1986-87 as a panel study of rural households The parameters of the model are estimated using the standard maximum likelihood Tobit approach Most of the results are consistent with the findings in other developing countries The results confirm that the level of human capital plays an important role in making decisions providing for labour in off-farm work activities The study also highlights the fact that farm-to-market roads and village electrification are some of the development strategies vital to encourage participation in off-farm work

Household Portfolio Allocation in the Netherlands: Saving Accounts versus Stocks and Bonds

Abstract: This paper analyzes the portfolio structure of households in the Netherlands. It considers the allocation of financial wealth to two major asset categories, namely saving accounts on the one hand and stocks and bonds on the other hand. The latter category is considered to be more risky than the former. We analyze the impact of the overall level of wealth, the marginal tax rate, and other variables on the allocation between assets, using cross-section data drawn in 1988 that provide detailed information on the structure of household wealth, not only on ownership but also on the amounts of wealth held in the respective asset categories. The econometric specification is a trivariate tobit type model. One equation explains the total level of wealth, a second one explains individual threshold values below which no wealth is held. The third equation explains the share of wealth invested in stocks and bonds. The model is estimated using Full Information Maximum Likelihood. Limited information provided by the data (non reporting) is explicitly taken into account. Results show that wealth and the marginal tax rate are major determinants of the allocation between safe and risky assets.

Transactions methods among US wholesale nurseries

Abstract: Change of product ownership in competitive agricultural industries is a critical event, yet little research has examined the transaction methods used by firms and the corresponding factors that influence the choice of transaction method. A sample of landscape plant nurseries across the United States provided data to model this decision. Transaction methods included sales by telephone, personal visits, mail order, and at trade shows. In addition, factors that influenced negotiated sales were investigated. Influential factors included age of the business, size (as measured by gross sales), location, market channel use, ownership structure, and perspective on competitive situation. Using a tobit estimation procedure, profiles of nursery firms more likely to use a particular transaction method were developed. © 1995 by John Wiley & Sons, Inc.

Discrimination by Formal Lenders in South Africa

Abstract: Censored (Tobit) regression is used to estimate the effects of race, location of residence, and sex of the household head on formal debt held by South African households. The magnitude of the effects suggests that lenders discriminate and that formal financial markets could be improved even without technical innovation.