Investigating uncertainty in macroeconomic forecasts by stochastic simulation

We investigate four sources of uncertainty with CPB’s macroeconomic model SAFFIER: provisional data, exogenous variables, model parameters and residuals of behavioural equations. Uncertainty is an inherent attribute of any forecast. We apply a Monte Carlo simulation technique to calculate standard errors for the short-term and medium-term horizon for GDP and eight other macroeconomic variables. The results demonstrate that the main contribution to the total variance of a medium-term forecast emanates from the uncertainty in the exogenous variables. For the short-term forecast both exogenous variables and provisional data are most relevant.

Are houses overvalued in the Netherlands?

The movement of the level of house prices in the Netherlands between 1980 and 2007 is explainable fairly well by fundamental supply and demand factors. Empirical research has shown that the overvaluation of approximately 10% that existed in 2003 shrunk to approximately 0% in 2007. This was not caused by downward correction of house prices, but by the circumstance that the increase of the actual house price between 2003 and 2007 lagged behind the increase of the long-term value of the house price. Therefore, this does not confirm the IMF's recently published research results, indicating that approximately 30% of the house price increase between 1997 and 2007 cannot be explained by fundamental factors.

SAFFIER; a multi-purpose model of the Dutch economy for short-term and medium-term analyses

Since late 2004, CPB Netherlands Bureau for Economic Policy Analysis has been using the macro-econometric model SAFFIER for its short-term and medium-term analyses. This model resulted from the integration of the quarterly model SAFE and the yearly model JADE. SAFFIER is a multi-purpose model. The quarterly version of the model, used for short-term analyses, only differs from its yearly version, used for medium-term analyses, in the specification of the lag structures. All other (non-technical) specifications are identical in both versions of the model. Simultaneously with the integration of SAFE and JADE, some innovations with respect to the modelling of the wage rate, private consumption, exports, the public sector and the house-price development have been incorporated. In the wage equation, the elasticity of the replacement rate is no longer constant, but is depending on the actual labour-market situation. This publication sketches the outlines of the SAFFIER model, focusing on the main innovations. In order to explain the working of the model, the results from a number of standard shocks are presented.

Decomposition of GDP-growth in some European Countries and the United States

The composition of economic growth can be analyzed in two different ways. In the 'traditional method' for the decomposition of GDP growth, total imports are deducted from exports. This approach underestimates the importance of exports for the growth in GDP, and overestimates the importance of domestic expenditure categories. In the alternative methodology proposed in this paper, imports are allocated to all expenditure categories. Although this 'import-adjusted method' is more complex than the 'traditional method', it has the considerable advantage that the contributions of the expenditure categories to GDP growth provide a better understanding of why GDP growth decelerates or accelerates. The methodology and data requirements for calculating the import content of final demand, and the implications for the decomposition of real GDP growth, are discussed. For six European countries and the United States, the paper shows that applying the alternative methodology provides rather a different economic story.

Decomposition of GDP growth in European countries; different methods tell different stories

The composition of economic growth can be analysed in two different ways. In the 'traditional method' for the decomposition of GDP growth, total imports are deducted from exports. This approach underestimates the importance of exports for the growth in GDP, and overestimates the importance of domestic expenditure categories. In the alternative methodology proposed in this paper, imports are allocated to all expenditure categories. Although this 'import-adjusted method' is more complex than the 'traditional method', it has the considerable advantage that the contributions of the expenditure categories to GDP growth provide a better understanding of why GDP growth decelerates or accelerates. The methodology for calculating the import content of final demand, and the implications for the decomposition of real GDP growth, are discussed. For six individual European countries and the euro area, the paper shows that applying the alternative methodology provides rather a different economic story.

On the optimality of expert-adjusted forecasts

Official forecasts of international institutions are never purely model-based. Preliminary results of models are adjusted with expert opinions. What is the impact of these adjustments for the forecasts? Are they necessary to get 'optimal' forecasts? When model-based forecasts are adjusted by experts, the loss function of these forecasts is not a mean squared error loss function. In fact, the overall loss function is unknown. To examine the quality of these forecasts, one can rely on the tests for forecast optimality under unknown loss function as developed in Patton and Timmermann (2007). We apply one of these tests to ten variables for which we have model-based forecasts and expert-adjusted forecasts, all generated by the Netherlands Bureau for Economic Policy Analysis (CPB). For almost all variables the added expertise yields better forecasts in terms of fit. In terms of optimality, the effect of adjustments for the forecasts is limited, because for most variables the assumption that the forecast are not optimal can be rejected for both the model-based and the expert-adjusted forecasts.

A leading indicator for the Dutch economy; methodological and empirical revision of the CPB system

Since 1990, CPB Netherlands Bureau for Economic Policy Analysis (CPB) has used a leading indicator in preparing short-term forecasts for the Dutch economy. This paper describes some recent methodological innovations as well as the current structure and empirical results of the revised CPB leading indicator. Special attention has been paid to the role and significance of IFO data. The structure of the CPB leading indicator is tailored to its use as a supplement to model-based projections, and thus has a unique character in several respects. The system of the CPB leading indicator is composed of ten separate composite indicators, seven for expenditure categories (‘demand’) and three for the main production sectors (‘supply’). This system approach has important advantages over the usual structure, in which the basis series are directly linked to a single reference series. The revised system, which uses 25 different basic series, performs quite well in describing the economic cycle of the GDP, in indicating the upturns and downturns, and in telling the story behind the business cycle.

A Leading Indicator for the Dutch Economy – Methodological and Empirical Revision of the CPB System

Since 1990 the Netherlands Bureau for Economic Policy Analysis (CPB) uses a leading indicator in preparing short-term forecasts for the Dutch economy. This paper describes some recent methodological innovations as well as the current structure and empirical results of the revised CPB leading indicator. Special attention is paid to the role and significance of IFO data. The structure of the CPB leading indicator is tailored to its use as a supplement to model-based projections, and thus has a unique character in several respects. The system of the CPB leading indicator is composed of ten separate composite indicators, seven for expenditure categories (‘demand’) and three for the main production sectors (‘supply’). This system approach has important advantages over the usual structure, in which the basis series are directly linked to a single reference series. The revised system, which uses 25 different basic series, performs quite well in describing the economic cycle of GDP, in indicating the upturns and downturns, and in telling the story behind the business cycle.leading indicator, short-term forecasts

Evaluating CPB's published GDP growth forecasts; a comparison with individual and pooled VAR based forecasts

We compare the accuracy of our published GDP growth forecasts from our large macro model, SAFFIER, to those produced by VAR based models using both classical and Bayesian estimation techniques. We employ a data driven methodology for selecting variables to include in our VAR models and we find that a randomly selected classical VAR model performs worse in most cases than the Bayesian equivalent, which performs worse than our published forecasts in most cases. However, when we pool forecasts across many VARs we can produce more accurate forecasts than we published. A review of the literature suggests that forecast accuracy is likely irrelevant for the non-forecasting activities the model is used for at CPB because they are fundamentally different activities.

Posttreatment Ischemic Lesion Evolution Is Associated With Reduced Favorable Functional Outcome in Patients With Stroke

BACKGROUND AND PURPOSE: Ischemic lesion volume can increase even 24 hours after onset of an acute ischemic stroke. In this study, we investigated the association of lesion evolution with functional outcome and the influence of successful recanalization on this association. METHODS: We included patients from the MR CLEAN trial (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) who received good quality noncontrast CT images 24 hours and 1 week after stroke onset. The ischemic lesion delineations included infarct, edema, and hemorrhagic transformation. Lesion evolution was defined as the difference between the volumes measured on the 1-week and 24-hour noncontrast CTs. The association of lesion evolution with functional outcome was evaluated using unadjusted and adjusted logistic regression. Adjustments were made for baseline, clinical, and imaging parameters that were associated P<0.10) in univariate analysis with favorable functional outcome, defined as modified Rankin Scale score of ≤2. Interaction analysis was performed to evaluate the influence of successful recanalization, defined as modified Arterial Occlusion Lesion score of 3 points, on this association. RESULTS: Of the 226 patients who were included, 69 (31%) patients achieved the favorable functional outcome. Median lesion evolution was 22 (interquartile range, 10–45) mL. Lesion evolution was significantly inversely correlated with favourable functional outcome: unadjusted odds ratio, 0.76 (95% CI, 0.66–0.86; per 10 mL of lesion evolution; P<0.01) and adjusted odds ratio: 0.85 (95% CI, 0.72–0.97; per 10 mL of lesion evolution; P=0.03). There was no significant interaction of successful recanalization on the association of lesion evolution and favorable functional outcome (odds ratio, 1.01 [95% CI, 0.77–1.36]; P=0.94). CONCLUSIONS: In our population, subacute ischemic lesion evolution is associated with unfavorable functional outcome. This study suggests that even 24 hours after onset of stroke, deterioration of the brain continues, which has a negative effect on functional outcome. This finding may warrant additional treatment in the subacute phase