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CHAPTER 3: TESTING THE OUT-OF-SAMPLE FORECASTING ABILITY OF A FINANCIAL CONDITIONS INDEX FOR SOUTH AFRICA15
INTRODUCTION
The previous chapter constructed a financial conditions index (FCI) for South Africa to capture in a single indicator the full spectrum of financial variables that affect the South African economy. The aim of this chapter is to investigate whether that FCI can act as an „early warning indicator‟ for impending macroeconomic instability caused by deteriorating financial conditions by means of out-of-sample forecasting tests. The premise here is based on the fact that asset prices (a major component of the FCI) are regarded as useful predictors of inflation and output growth (Stock and Watson, 2003)16. However, forecasts based on individual asset prices tend to be unstable, and combination approaches are preferable (Stock and Watson, 2003). To this end I test whether the estimated FCI does better than its individual financial components in forecasting key macroeconomic variables, namely output growth, inflation and an interest rate.
This forecasting exercise is conducted with caution, and the techniques are chosen specifically to hopefully address issues associated with the use of asset prices in forecasting real economic activity noted by Stock and Watson (2003:801) (remembering that the FCI largely comprises asset prices): namely, the “underlying relations themselves depend on economic policies, macroeconomic shocks, and specific institutions and thus evolve in ways that are sufficiently complex that real-time forecasting confronts considerable model uncertainty”. The concept „forecast encompassing‟ is used to examine the forecasting ability of these variables following Rapach and Weber (2004). They consider the forecasting power of ten financial variables with respect to real GDP growth and industrial production growth in the US over the period 1985M01 to 1999M04, to test and complement a similar study by Stock and Watson (2003)17. The forecast encompassing approach used in this chapter is based on two sets of out-of-sample forecasts for output growth, inflation, and the Treasury Bill yield. The two forecasts are obtained from an autoregressive distributed lag (ARDL) model including one financial variable at a time, and a benchmark autoregressive (AR) model. An optimal composite forecast is formed as the convex combination of these two forecasts and is interpreted as follows: if the optimal weight attached to the ARDL model‟s forecast is zero, then the ARDL model does not contain information that is useful for forecasting the chosen macroeconomic variable apartfromtheinformationalready contained in the AR benchmark model. In other words, the AR model‟s forecasts encompass those of the ARDL model. Instead, if the optimal weight attached to the ARDL model‟s forecast is larger than zero, then the ARDL model doescontain information that is useful for forecasting the chosen macroeconomic variables in addition to the information already contained in the AR benchmark model. The generic null hypothesis for these tests can then be stated as: the AR benchmark out-of-sample forecast encompasses the ARDL out-of-sample forecast (where the ARDL model includes the selected financial variable or the FCI); i.e. that the AR model is the “better” forecasting model, which implies that the selected financial variable or FCI is not relevant in forecasting the chosen macroeconomic variable.
So for each financial variable and the FCI, recursive out-of-sample forecasts of manufacturing output growth, inflation and the Treasury Bill yield are constructed over the out-of-sample period of 1986M01–2012M01, using an ARDL model that includes the chosen financial variable or FCI as an explanatory variable. As suggested by Rapach and Weber (2004), I test the above null hypothesis of an encompassing AR model forecast using various statistics proposed by Harvey, Leybourne and Newbold (1998) and Clark and McCracken (2001).
The remainder of the chapter is organised as follows: Section 3.2 presents a brief discussion of the data used in the forecast encompassing exercises; while Section 3.3 presents Rapach and Weber‟s (2004) econometric methodology used in the forecast encompassing tests, including derivations of the five test statistics used for inference. The empirical out-of-sample forecast results are presented in Section 3.4, along with adjustments made to the test statistics so as to account for data-mining, as well as discussions of the individual predictors‟ economic significance (for those predictors surviving data-mining), and Section 3.5 provides the forecasting performance of the estimated FCI. Section 3.6 concludes the chapter.
DATA
In compiling the FCI in the previous chapter, I choose series that encompass measures in levels, as well as volatility measures. The data series included in the compilation of the FCI are found in Table 1 in Chapter 2, and are discussed in Section 2.5. The data set covers the sample of 1966M02 – 2012M01. The data series used in the forecasting exercises in this chapter include: the estimated FCI; each of its sixteen individual component series; a measure of output growth – the month-on-month rate of change in South Africa‟s Manufacturing Production Index; a measure of inflation – the month-on- month rate of change in the CPI; and the 3-month Treasury Bill yield. The latter three series are the macroeconomic variables with respect to which I test the FCI‟s forecasting ability. Figure 2 shows the three macroeconomic series compared graphically to the estimated FCI.
ECONOMETRIC METHODOLOGY
The forecast encompassing test used in this research follows Rapach and Weber (2004), and more details on the econometric methodology can be found in that paper. I consider the unrestricted ARDL model:
where is the variable of interest to be forecasted (manufacturing growth, Treasury Bill yield and inflation), q1 and q2 are the ARDL lags, is the FCI or one of the sixteen financial variables used in the construction of the FCI, and his the forecast horizon (set to a maximum of 24 months in this instance)18. The following recursive procedure is used to simulate the out-of-sample forecasting ability of the individual financial data series and the FCI: First, divide the total sample of T observations into the in-sample period, spanning Robservations, and the out-of-sample period, spanning Pobservations (in this instance, the out-of-sample period is 1986M01–2012M01).
Theil‟s U Test
If the root mean squared forecast error (RMSFE) of the unrestricted ARDL model (RMSFEUR) is less than the RMSFE of the restricted model (RMSFER), then this model is the “better” forecasting model with lower forecasting error. Therefore, if , a result of U< 1 will indicate that the unrestricted ARDL model (i.e. the model including the financial variable or FCI as a predictor) forecasts are superior to those of the simple AR model19.
Bootstrapping Procedure
The bootstrapping procedure used to enable inference of these test statistics (from Rapach and Weber, 2004) is Clark and McCracken‟s (2007) version of Kilian (1999). Suppose, under H0: the financial variable has no forecasting power with respect to, that:
For a detailed exposition of the recursive procedure used in conducting the bootstrapping used in this chapter, refer to Rapach and Weber (2004:721-722). Each of the four test statistics described in Equations (13), (14), (17) and (22) are calculated 500 times, resulting in empirical distributions for these statistics. The p-value for each is the proportion of the bootstrapped statistic greater than the original statistic.
The estimated out-of-sample test statistics for the FCI are reported in Table A3 in Appendix A.5, and are summarised along with the results for all sixteen financial variables in Table 5, Table 6 and Table 7 below. The results are based on the Akaike Information Criterion (AIC) and are for forecast horizons of 1, 3, 6, 9, 12, 15, 18, 21 and 24 months. Values for and are considered from 0 up to 24. The results are representative of the out-of-sample period of 1986M01–2012M01. Similar results for the out-of-sample periods 1973M01–2012M01 and 2000M01–2012M01 are available upon request.
CHAPTER 1: Introduction
1.1 Background
1.1.1 Identify an appropriate FCI for South Africa
1.1.2 Use the identified FCI in forecasting exercises of major macroeconomic variables
1.1.3 Use the identified FCI in structural analysis exercises in a vector autoregression (VAR) framework
1.2 Importance and Benefits of the Study
1.3 Outline of the study
CHAPTER 2: Identifying a financial conditions index for South Africa
2.1 Introduction
2.2 Literature review
2.3 Econometric methodology
2.4 Data
2.5 Empirical Results
2.5.1 FCI Indices
2.5.2 Evaluating the performance of FCI indices
2.6 In-sample causality testing
2.7 Conclusions
CHAPTER 3: Testing the Out-of-Sample Forecasting Ability of a Financial Conditions Index for South Africa
3.1 Introduction
3.2 Data
3.3 Econometric Methodology
3.4 Empirical Results
3.5 An Illustration as of 2012M02
3.6 Conclusions
CHAPTER 4: Testing the Asymmetric Effects of Financial Conditions in South Africa: A Nonlinearn Vector Autoregression Approach
4.1 Introduction
4.2 Data
4.3 Econometric Methodology
4.4 Empirical Results
4.5 Conclusions
CHAPTER 5: General conclusions and areas of future research
5.1 Introduction
5.2 Summary of key findings
5.3 Contributions of this study
5.4 Areas of future research
REFERENCES
APPENDICES
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