Economics - Research Publications

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    Discrete hours labour supply modelling: specification, estimation and simulation
    Creedy, J. ; Kalb, G. R. ( 2005-03)
    The assumption behind discrete hours labour supply modellingis that utility-maximising individuals choose from a relatively smallnumber of hours levels, rather than being able to vary hours workedcontinuously. Such models are becoming widely used in view of theirsubstantial advantages, compared with a continuous hours approach,when estimating and their role in tax policy microsimulation. Thispaper provides an introduction to the basic analytics of discrete hourslabour supply modelling. Special attention is given to model specification,maximum likelihood estimation and microsimulation of taxreforms. The analysis is at each stage illustrated by the use of numericalexamples. At the end, an empirical example of a hypotheticalpolicy change to the social security system is given to illustrate the roleof discrete hours microsimulation in the analysis of tax and transferpolicy changes.
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    Behavioural microsimulation modelling with the Melbourne Institute Tax and Transfer Simulation (MITTS): uses and extensions
    Creedy, J. ; Kalb, G. R. ( 2005-03)
    This paper describes microsimulation modelling in non-technical terms; and it explainswhat can be achieved with microsimulation modelling in general, and the MelbourneInstitute Tax and Transfer Simulator (MITTS) in particular. The focus is onbehavioural microsimulation modelling, which takes individuals’ labour supplyresponses into account when analysing tax and transfer reforms. Microsimulationmodels are built to replicate closely the considerable degree of heterogeneity observedin the population. Several examples of recent uses of MITTS are given and brieflydescribed. In addition, one worked-out example is presented to illustrate some of thefeatures and typical outputs of MITTS. Given the relatively recent development ofbehavioural microsimulation models, there are several opportunities for furtherextensions. For example, it would be valuable to allow for the demand side of labour,indicating whether new labour force participants are likely to find work; or to allow forlife-cycle dynamics, which are important to deal with population-ageing issues or withfemale labour force participation.
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    Accounting for population ageing in tax microsimulation modelling by survey reweighting
    Cai, L. ; Creedy, J. ; Kalb, G. R. ( 2005-03)
    This paper investigates the use of sample reweighting in a behavioural taxmicrosimulation model, to examine the implications for government taxes andexpenditure of population ageing in Australia. First, a calibration approach to samplereweighting is described, producing new weights which achieve specified populationtotals for selected variables, subject to the constraint that there are minimal adjustmentsto the weights. Second, the performance of the Australian Bureau of Statistics’ (ABS)weights provided with the 2001 Survey of Income and Housing Cost (SIHC) wasexamined and it was found that reweighting does not improve the simulation outcomesfor the 2001 situation, so the original ABS weights were retained for 2001. Third, theimplications of changes in the age distribution of the population were examined, basedon population projections to 2050. A ‘pure’ change in the age distribution wasexamined by keeping the aggregate population size fixed and changing only the relativefrequencies in different age-gender groups. Finally, the effects of a policy change tobenefit taper rates in Australia were compared for 2001 and 2050 population weights. Itis suggested that this type of exercise provides an insight into the implications ofchanges in the population on government income tax revenue and social securityexpenditure, indicating likely pressures for policy changes.
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    Confidence intervals for policy reforms in behavioural tax microsimulation modelling
    Creedy, J. ; Kalb, G. R. ; Kew, H. ( 2005-03)
    This paper addresses the need for a measure of the uncertaintythat is associated with the results calculated through tax policy behaviouralmicrosimulation modelling. Deriving the analytical measurewould be extremely complicated, therefore, a simulated approach isproposed which generates a pseudo sampling distribution of aggregatemeasures based on the sampling distribution of the estimated laboursupply parameters. This approach, which is very computer intensive,is compared to a more time-efficient approach where the functionalform of the sampling distribution is assumed to be normal. The resultsshow that in many instances the results from the two approachesare quite similar. The exception is when aggregate measures for minortypes of payments, involving relatively small groups of the population,are examined.