FONDATION POUR LES ETUDES ET RECHERCHES SUR LE DEVELOPPEMENT INTERNATIONAL Measuring macroeconomic volatility Applications to export revenue data, 1970-2005 by Joël Cariolle Policy brief no. 47 March 2012 The FERDI is a Public Interest Foundation. In cooperation with the Fonddri it implements the Initiative for Development and Global Governance (IDGM). In cooperation with the Iddri and the Cerdi it implements the IDGM+ project “Laboratoire d’excellence.” 1 Measuring volatility: applications to export revenue data, 1970-2005. By Joël Cariolle Joël Cariolle is a research assistant at the FERDI. Contact: [email protected] The literature on macroeconomic volatility covers an extremely wide field, reflected in the very broad spectrum of indicators used to grasp this phenomenon. The choice of indicator is generally little discussed, on the grounds that the different methods give rise to volatility scores that are strongly correlated. However, while these indicators do seem to converge when used to measure the average magnitude of volatility, they diverge significantly when one studies its asymmetry (predominance of positive or negative shocks) or the occurrence of extreme deviations. The volatility of an economic variable refers to the notion of disequilibrium, measured by the deviation between the values taken by this variable and a reference value or a trend. The first stage is therefore to identify and isolate the trend or permanent component of the change in an economic variable. Traditionally, volatility indicators measure the mean deviation range of the variable relative to the reference value, generally on the basis of standard deviation. But such an approach masks other important dimensions of volatility, such as the asymmetry of the deviations (predominance of positive or negative shocks) and the occurrence of extreme deviations. Economic agents may behave or react quite differently depending on whether the volatility is dominated by positive or negative shocks, but also on whether the shocks are frequent and weak or infrequent and strong. We illustrate our analysis based on the annual changes in the export revenues of 134 developed and developing countries over the period 1970-2005 from the World Development Indicators. Calculation of trend components or reference values The first stage is to identify the trend component of an economic variable in order to measure the deviations between the values taken by that variable and that trend or reference. Since this first stage may influence the volatility indicators, we put forward here several methods for calculating the reference. The first two methods are based on a parametric approach in which the trend, which takes a mixed (deterministic and random) form, is estimated econometrically: yt = α + βt + δyt −1 + ε t 2 The trend or reference value is then yˆ t = α + βˆt + δˆy t −1 and the deviation is εˆt = yt − yˆ t . The first alternative is to estimate the trend over the whole period (the so-called “global” trend); the second is to estimate the trend on a rolling basis for each year based on the data for each year and that of the twelve previous years (the “rolling” trend). The other two methods of trend computation are based on the Hodrick-Prescott filter. The HP trend is derived from the algorithm: − ∗ and the deviation is = − +λ ∆ ∗ The two alternatives are obtained by selecting a smoothing parameter (λ) of 6.5 or 100, generating respectively a fluctuating or a stable trend. The four reference values and the deviations they generate are illustrated in Figure 1 below, for the case of Argentina. Figure 1. Reference values applied to the case of Argentina Filter method 0 0 2,000e+10 2,000e+10 4,000e+10 4,000e+10 Parametric method 1970 1980 1990 2000 1970 1980 Year Exports (USD, 2000) Rolling mixed trend 1990 2000 Year Global mixed trend Exports (USD, 2000) Filtered exports (λ=100) Filtered exports (λ=6.5) 3 0 -20 -40 as % of trend 20 40 60 Deviations compared (as % of trend) 1970 1980 1990 2000 Year Rolling mixed trend Global mixed trend HP filter (6.5) HP filter (100) Magnitude of volatility The most commonly used method is to compute the standard deviation (StdDev) of the variable around its reference value. Here we normalize the deviations by the reference value so as to make them comparable between countries. The formula is the following: 1 yt − reft StdDev = 100 × ∑ T t reft 2 with T=[1982;2004-05] where ref t is one of the four reference values previously presented ( yˆ t over the whole period, or rolling, or HPt of HP filter 6.5 or HP filter 100). Table 1 shows that the indicators of magnitude derived from the different reference values are very strongly correlated. Table 1. Correlations among volatility magnitude indicators (1) Global mixed trend (2) Rolling mixed trend (3) HP 6.5 (4) HP 100 Volatilities calculated over period 1982-2004/05 (1) 1.00 (2) 0.92* 1.00 (3) 0.96* 0.95* 1.00 (4) 0.87* 0.80* 0.87* 1.00 * Significant at 5%. Sample = 134 countries. 4 Asymmetry of volatility Indicators of magnitude do not make it possible to identify a possible asymmetry of shocks. The coefficient of asymmetry (CA), or dissymmetry, identifies the profile of the volatility by revealing whether it is dominated by negative or positive shocks. This coefficient is calculated as follows: CA = 100 × 1 yt − ref t ∑ T t ref t 1 y − ref t t T ∑ ref t t 3 2 3/ 2 with T = 1,..., t A symmetrical distribution of deviations gives a coefficient equal to zero, while a distribution dominated by positive (negative) deviations gives a positive (negative) CA. The greater the positive or negative shocks, the higher the CA. Erreur ! Source du renvoi introuvable. 2 shows that the correlations among the CA derived from the different reference values are weak, suggesting that the choice of reference values is primordial when one is interested in the asymmetry of shocks. Table 2. Correlations among coefficients of asymmetry (CA) calculated over the period 1982-2005. (1) CA (Global mixed trend) (2) CA (Rolling mixed trend) (3) CA (HP(6.5)) (4) CA (HP(100)) CA calculated over the period 1982-2005 (1) 1 (2) 0.23* 1 (3) 0.08* 0.14* 1 (4) 0.29* 0.02 0.65* 1 * Significant at 10%. Sample = 134 countries. Figure 2 in the appendix shows a positive but weak correlation between measures of magnitude and measures of asymmetry: two countries may have a similar magnitude of volatility but exhibit a radically different asymmetry. The asymmetry of the deviations from the reference value is thus a distinct dimension of volatility, which cannot be grasped by magnitude indicators alone. 5 Frequency of extreme deviations A final dimension of the volatility of a macroeconomic variable concerns the occurrence of extreme deviations. This dimension is measured by the fourth aspect of the distribution of observations around their reference value, kurtosis (or coefficient of peakedness). The kurtosis of normalized deviations is calculated by means of the following formula: Kurtosis = 100 × 1 T y − ref ∑t t ref t t 1 T y − ref ∑t t ref t t 4 2 2 with T = 1,..., t Kurtosis indicates the extent to which observations close to the mean are numerous relative to observations distant from it. In the case of a normal distribution kurtosis is equal to 3 (or 300% when expressed as a percentage of the trend). A higher kurtosis value represents a staggered distribution with thick distribution tails, whereas a lower value represents a distribution concentrated around its mean with thin distribution tails. Combined with the coefficient of asymmetry, the kurtosis can provide information on a country’s propensity to undergo extreme negative or positive shocks. Table 3 sets out the correlations among the kurtoses derived from four trends or reference values. These correlations are stronger than those of the asymmetries but weaker than those of the volatility magnitude indicators, showing that the choice of reference values influences the diagnosis on the occurrence of extreme shocks. Table 3. Correlations among kurtoses calculated over the period 1982-2004/05. (1) Kurt. (Global mixed trend) (2) Kurt. (Rolling mixed trend) (3) Kurt. (HP(6.5)) (1) 1 (2) 0.39* 1 (3) 0.38* 0.28* 1 (4) 0.49* 0.22* 0.62* (4) Kurt. (HP(100)) 1 * Significant at 5%. Sample = 134 countries. Figure 3 in the appendix shows that the correlation between the measures of magnitude and the measures of kurtosis is relatively weak, indicating that the two dimensions are relatively independent. Figure 4 shows the correlation between the asymmetry scores and the kurtosis scores. A U-shaped relationship can be observed between these two measures: at negative and 6 weakly positive levels of asymmetry, the two dimensions are relatively independent, whereas high kurtosis is associated with strong positive asymmetry, for the export data used here. Overall, the three measures of magnitude, asymmetry and kurtosis appear relatively independent, at least for the data used here, which leads us to consider that these three dimensions generate different information on volatility. It is therefore important to use several types of indicators in relation to the subject studied, or if one wants to establish a complete diagnosis on volatility. The method is set out in detail in: Cariolle J. (2012), Mesurer l’instabilité macroéconomique: applications aux données de recettes d’exportation, 1970-2005, FERDI Working Paper No.I.14. If you use these data, please cite this reference, adding: “Data available at: http://www.ferdi.fr/en/Innovative-indicators.html”. 7 ANNEXE : Figure 2. Correlation between measures of magnitude and of asymmetry of volatility, by reference value. Rolling mixed trend Global mixed trend Correlation = 36% 80 60 Correlation = 23% KIR TCD Magnitude 40 60 40 SLE 100 Asymmetry 200 0 -200 300 -100 0 100 200 DOM 300 Asymmetry HP filter 6.5 HP filter 100 Correlation = 18% Correlation = 38% LAO 50 0 50 -100 UGA KWT SLE ALB IRN SOM GHA GNBNGATCD RWA HTI ARG COM SUR SAUAGO SLB ZAR TON GAB STP TGO DZA BDI LSO NIC BFA PER COG NER PRY PNG GUY ZMB OMN BGD SLV BGR ARE SWZ VEN ETH SEN CMR BEN MWI DMA BOL VCT TTO SYR TUR ATGLAO MDG BWA BHR NAM ECU EGY GMB MOZ IDN NPL CIV CAF MRT MLT MLI BLZ PRT CRI DEU HUN URY BTN AUT CHE COL LKA HND CHL MEX ZWE GRC ISL BRB LCA CYP GTM BEL MUS PAN KNA FJI SWE MAR BRA PAK AUS KOR KEN MYS ZAF ITA DNK PHL SYC TUN FIN THA VUT FRA JAM ESP HKG IRL IND LUX JOR MAC NZL NLD JPN NOR CHN CAN PRI ISR USA GBR 20 IRN KWT ALB GNB UGA HTI BDI SOM NGA DOM GHA COM SURRWA ZAR TON STP SAU SLB DZABFA MDG ARG GAB COG PRY PNG NIC AGO BGD BGR LAO LSO VEN OMN TGO SLV ZMB SWZ NER PER VUT BTN CMR DMA ARE BEN GUY ATG MWI GMB SYR BWA TTO ETH NPL BOL CAF ZWE CIV BLZ SEN LCA URY KNA VCT MOZ MUS BHR MRT CRI ECU IDN CHL MLT HUN MLI TUR FJI PAN NAM COL PRT PHL HND ZAF EGY THA DEU CYP AUT GRC ISL GTM KEN BRA PAK BRB KOR HKG MEX MYS LKA LUX FIN SWE MAR BEL ITAIRL CHE SYC TUN IND DNK JPN PRI AUS JOR FRA CHN ESP NZLCAN JAM NOR NLD MAC ISR GBR USA 0 20 Magnitude KIR KIR Magnitude 20 30 40 Magnitude 20 30 40 KIR TCD HTI GNB SLE IRN SOM NGA UGA GHABDI RWA SUR ZAR COM SLB GAB BFA COG STP AGO DZA SAU PNG TON LAO ARG LSO NIC OMN NER BGR MWIPERVUT BEN MDG TGO VEN SLV SWZ GUY ZMB PRY BGD BTN SYR CAF DMA ATG CIV GMB ETH ECU BOL ARE MOZ TTO KNA BWA BHR CRI CMR COL BLZ URY NPL PAN ZAF SEN MLI ZWE EGY MUS MLT NAM FJI HND LCA BRA VCT GTM TUR GRC HUN CHL ISL FIN SYC MEX MRT KOR CHE AUT DEU KENISR SWE PRT LUX IDN LKA PHL JOR BRB MYS IND BEL PRI ITA PAK CHN NZL ESP FRA MAR DNK AUS JPN NOR CYP TUN THA NLD IRL MAC JAM HKG GBR CAN USA -200 ALB -100 0 Asymmetry 100 10 DOM DOM 0 0 10 KWT TCD SLE HTI SOM UGA ALB IRN NGA GNB GHA SUR KWT RWA COM BGR SAU SLB GABPRYBDI BFAZAR VUT PNG TGO LSO COG STP NIC DZA TON BTN MOZ AGO PER SLV ATG GUY SWZ NER ETH OMN ZMB MWI SYR BWA ARG DMA GMB BEN KNA ARE MDG NPL CIV VEN MLT CAF CMR EGY SEN PRT ZWE ECU ZAF MUS LCA NAM HND THA AUT URY VCT SYC BGD HUN MLI IDN DEU ISL TTO CHE MEX CRI LUX BLZ BOL BEL PAN COL SWE PHL HKG CHL MRT BHR DNK CHN FIN GRC KOR ITA MYS MAR BRB FRA BRA CYP GTM FJI TUR IND LKA PRI KEN PAK NLD MAC TUN ESP JPN NOR ISR JOR AUS GBR JAM IRL CANNZL USA 200 -200 -100 0 100 Asymmetry 200 300 Figure 3. Correlation between measures of magnitude and of peakedness of volatility, by reference value. Rolling mixed trend Global mixed trend Correlation = 20% KIR 80 60 Correlation = 29% TCD 60 40 UGA KWTIRN SLE ALB TCD NGA SOM GHA RWA GNB HTI ARG COM AGO SAU SUR SLB ZAR TON STP GAB TGO DZA BDI LSO NIC BFA PER NER COG PNG PRY GUY ZMB OMN BGD SLV BGR ARE SWZ VEN ETH SEN BEN MWI CMR DMA BOL VCT TTO SYR TUR BWA MDG BHR ATG NAM HUN EGY ECU MOZ GMB NPL IDN CIV MRT CAF LAO MLT LKA MLI CRI BLZ PRT DEU BTN URY AUT COL CHE HND CHL LUX ISL GRC ZWE MEX CYP LCA GTM BRB BEL KNA MAR BRA PAK MUS SWE PAN FJI AUS KOR KEN MYS ZAF ITA DNK SYC TUN THA FIN PHL VUT JAM FRA HKG PRI IND ESP IRL MAC NZL NLD JOR JPN NOR CHN CAN ISR GBR USA 20 UGA DOM Magnitude 40 SLE DMA LAO 0 IRN ALB KWT GNB HTI NGA SOMBDI GHA RWA COM SUR ZAR TON STP SAU SLB BFA DZA ARG MDG GAB COG PRY PNG NIC AGO BGD BGR LSO OMN VEN TGO SLV NER SWZ VUT PERBTN CMR ZMB ARE GUY MWI BEN ATG GMB SYR BWA TTO ETH NPL BOL CAF ZWE CIV BLZ KNA SEN LCAHUN URY VCT MOZ MUS BHR MRT CRI ECU MLT CHL MLI TUR COL PAN FJI NAM PRT PHL HND ZAF IDN EGY CHE THA AUT DEU GRC CYP ISL KEN HKG BRA PAK KOR BRB LUX FIN MYS LKA MEX GTM BEL SWE MAR ITA IND SYC TUN DNK AUS PRI JPN FRA JOR CHN ESP NZL JAM NLD MAC NOR ISR IRL GBR U SA CAN 0 20 Magnitude KIR 200 400 600 800 1000 0 500 HP filter 100 Correlation = 41% LAO 50 50 HP filter 6.5 Correlation = 37% KIR 200 400 600 Peakedness 800 20 30 Magnitude BGD 10 DOM TCD HTI SLE SOM UGA ALB IRN GHA NGA GNB SUR KWT BGR COM RWA SAU SLB ZAR GAB BDI BFA PRY VUT PNG TGO LSO COG STP DZA NIC BTN TON MOZ AGO PER SWZ SLV ATG NER GUY ETH OMN ZMB MWI SYR BWA GMB DMA ARG BEN NPL CIV KNA MDGBGD CAF CMR ARE VEN MLT SEN EGY ZWE PRT ZAF ECU NAM HND LCA VCT URY AUT THA TTO MLI HUN SYC ISL DEU IDN MEX CHE CRI BOL BLZ LUX PAN BEL COL PHL SWE CHL MRT HKG BHRMUS FIN DNK CHN GRC KOR MYS ITA MAR BRB BRA TUR FRA FJI GTM CYP IND LKA PRI PAK KEN NLD IRL ESP MAC TUN NZL JPN NOR ISR JOR AUS GBR CAN JAM USA DOM 0 TCD HTI GNB SLE IRN ALB KWT SOM NGA UGA RWA COM SUR BDI GHA SLBZAR GAB BFA STP COG AGO DZA VUT PNG SAU TON LAO ARG NER LSO OMN NIC SLV MWI BGR BEN MDG TGO VEN SWZ ZMB GUY PRY SYR BTN CAF DMA CIV ATG PER GMB ETH ECU ARE BOL MOZ TTO KNA B WA CRI BHR CMR COL PAN SEN URY BLZ NPL ZAF ZWE MLI EGY NAM HND FJI VCT MUS BRA LCA TUR CHL GRCGTM FIN MLT ISL HUN KOR MEX SYC AUT MRT DEU C HE KEN PRT LUX SWE IDN PHL LKA JOR BRB MYS PAK ITA CHN IND NZL ESP PRI BEL MAR AUS FRA JPN DNK ISR NOR TUN CYP NLD THA IRL MAC GBR JAM HKG CAN USA 40 KIR 40 30 Magnitude 20 10 1500 Peakedness Peakedness 0 1000 DOM 1000 0 500 1000 1500 Peakedness 8 Figure 4. Correlation between measures of asymmetry and of kurtosis, by reference value. Rolling mixed trend 1500 UGA DOM LAO DMA TCD -100 0 100 200 1000 GHA BGD MDG HUN CMR LUX CHE LCA GTM SLE MEX BTN HTI COL MUS IRL PER BWA VEN CRI VUT ISLTUR DEU KWT ARG IDNTTO IRN DNK RWA MRT KOR SEN DZA ITA EGY CAF ARE ATG ALB LKA ZAR ECU OMN GUY NAM BOL BEL AUT JPN ZAF PRY KNA MAR ISR SWE SYC NICBGR JOR COM BFA IND NPL PAK SWZ SLV JAM BRB CAN KIR ZWE ZMB CYP VCT BEN MOZ TON COG HND NER PRT FRA THA BDI SLB KEN GAB MYS NOR PHL MLI AGO ETH BLZ TGO PRI BHR USA PNG GRC SYR CIV NZL SUR BRA MWI CHL ESP STP AUS URY GMB LSO CHN NLD HKG TUN FIN MLT GNB MAC FJI SOM SAU GBR PAN NGA 500 Peakedness DOM HUN NAM RWA LKA UGA CHE TUR COL GHA ATG BHR BEL ARG MEX DZA BRB LUX IRN KIR ZAR ZMB SEN FRA DNK DEU ZWE MDG AUT PER PHL JOR GMB IRL CAF ITA AUS BOL JAM SWZ CHL ZAFESP ZAF CMR OMN KWT ESP FJI GRC COG KEN ISLIND ISL SYR IND SLV NLD MRT VEN GUY PRT MLT ARE PRI ECU BFA SLE BWA PAN SLB SUR TCD ALB GAB LSO SWE NER SAU MUS BDI TTO NGA FIN URY HKG ETH PAK BGD CHN MLI MWI EGY PRY JPN BRA THA CRI NOR CAN MOZ LAOBLZ HND HTI AGOBGR KOR TGO USA GNB NIC DMA STP SOM CIV VCTISR TUN GBR BEN MAR GTM KNA B BTN TN COM MYS NZL PNG SYC MAC TON IDN NPL LCA VUT CYP 0 800 1000 600 200 400 Peakedness Global mixed trend 300 -200 -100 0 Asymmetry 0 Asymmetry 100 KIR 1500 LAO 1000 Peakedness MDG COL ECU MUS JOR COM GHA SLV PERVUT SYC ISR KEN LKA BDI ZAR NIC RWA ALBMEX ATG SLE BHR NZL ARG HND IDN SLB VEN HUN GUY KOR GTM EGY MYS TUR IND MOZ MLI BWA BFA OMN CYP BLZ TCD BEN MAR CRI BRB SUR ZMB IRN BGR AGO TON BTN HKG CHE LAO MAC UGAARE UGA LSO BOL MWI ARE GBR GRC JAM CHL ISL CIV URY DNK PRY ETH GNB PHL KNA NAM MRT COG USA SYR MLT TGO DMA BEL PRI ZWE THA SWE CAN STP PNG GAB NER SOM SEN VCT CAF AUT LUX LCA CMR CHN FIN ZAF DZA FRA JPN DEU ITA PAK BRA PAN TTO PRT NPL AUS GMB TUN FJI ESP NOR SAU IRL NGA NLD 500 HTI -100 300 DOM KWT HTI MUS SWZ BGD JOR VUT MDG GHA RWA BHR IRN CRI SYC MLT PER TCD ECU ISR COL BRB LUXKNA TON HUN VEN MAC GBR ALB IND SLV EGY PRI BDI GRC NIC ARG COM THA CHE ZAR BGR ARE SLE TUN BEL FRA ATG CYP JAM LKA LCA GUY IDN HND SUR CMR LSO MAR OMN NZL AUT ITA BWA BTN HKG URY STP MRT BLZ DEU AGO SLB PHL CHN NLD DNK ISL CIV MWI ZMB MOZ KOR NPL BEN PAN ETH PNG ZAF AUS GTM NOR KEN PRT JPN KIR DMA ESP GNB NAM NGA MLI SYR TUR CAN VCT BFA GAB SAU BOL MEX PRY COG CHL USA PAK TGO SEN MYS FJI NER SWE ZWE DZA UGA GMB BRA TTO CAF FIN IRL SOM 0 Peakedness 200 400 600 800 1000 DOM BGD -200 200 HP filter 100 HP filter 6.5 KWT SWZ 100 Asymmetry 200 -200 -100 0 100 200 300 Asymmetry 9
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