Australia's Cash Economy: Are the estimates credible?

The method of "excess sensitivity" of Bajada (1999, 2001, 2002) indicates a large underground economy in Australia, with estimates of unrecorded income around 15 per cent of official GDP. These estimates concern policymakers, especially those agencies responsible for national accounts, tax collection, economic stabilization and law enforcement. We show that the method exhibits a severe form of non-robustness, in which the results change markedly with a simple change in the units of measurement of the variables. There is a separate problem in which a key parameter is set to an unrealistic value that makes the estimates many times too high.underground economy, currency demand, tax evasion, econometric models

Estimating the Underground Economy using MIMIC Models

MIMIC models are being used to estimate the size of the underground economy or the tax gap in various countries. In this paper I examine critically both the method in general and three applications of the method by Giles and Tedds (2002), Bajada and Schneider (2005) and Dell’Anno and Schneider (2003). Connections are shown to familiar econometric models of linear regression and simultaneous equations. I also investigate the auxiliary procedures used in this literature, including differencing as a treatment for unit roots and the calibration of results using other data. The three applications demonstrate how the method is subjective and pliable in practice. I conclude that the MIMIC method is unfit for the purpose.underground economy, MIMIC, structural modelling, LISREL® software

Global Temperature Trends

Are global temperatures on a warming trend? It is difficult to be certain about trends when there is so much variation in the data and very high correlation from year to year. We investigate the question using statistical time series methods. Our analysis shows that the upward movement over the last 130-160 years is persistent and not explained by the high correlation, so it is best described as a trend. The warming trend becomes steeper after the mid-1970s, but there is no significant evidence for a break in trend in the late 1990s. Viewed from the perspective of 30 or 50 years ago, the temperatures recorded in most of the last decade lie above the confidence band of forecasts produced by a model that does not allow for a warming trend.Land and ocean temperatures; deterministic and stochastic trends; persistence; piecewise linear trends