A Description of Swedish Producer and Import Price Indices PPI, EXPI and IMPI

Transcription

1 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 1(11) A Descrpon of Swedsh roducer and por rce ndces E and M Approxaely prces are colleced onhly fro around copanes. The daa colleced are broken down no doesc producer prces expor and por prces and onhly prce ndces are calculaed for each of hese an groups. Wh soe excepons he survey's produc coverage spans agrculure and foresry fsheres nng and quarryng and anufacurng as well as elecrcy gas hea and waer supply (CA caegores A-E). The doesc producer prce ndex gauges he developen of prces for producs ha are anufacured and sold n Sweden. The expor prce ndex easures he producer prce changes for goods sold for expor whle he por prce ndex s he prce ndex for pored goods. The producer prce ndex cobnes he doesc and expor sales producer prce ndces. The prce ndces ha are calculaed onhly are lnked annually o he Deceber ndex of he prevous year. Daa are colleced roughly beween he 1s and he 20h of he onh afer he sascal onh concerned and are publshed around he 25h. Approxaely one-half of he daa are colleced va elephone (TDE) and os of he res by eans of shule fors. The prce daa relae o doesc producers' sellng prces and porers' purchase prces. Respondens are also requred o sae wheher here have been any changes o he specfcaons of he respecve goods. f hs s he case afer consulng he responden he Deceber base prce s adjused where approprae so ha qualy changes are facored ou of he prce coparson. Fgure 1: nerrelaonshps beween he varous prce ndces RODUCERS SELL RCE EORT MARKET RODUCERS SELL RCE DOMESTC MARKET MORT URCHASES Expor rce ndex E roducer rce ndex roducer rce ndex Hoe Sales HM rce ndex for Doesc Supply T por rce ndex M

2 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 2(11) 1 Objecve and background The prce ndex a he producer and por sage s nended o reflec he average prce developen boh overall and for varous produc groups. rces are easured respecvely a he frs dsrbuon sage where he goods are suppled by he Swedsh producer and a he frs purchasng sage where he goods ener Sweden. rce ndex seres wh a rough produc group breakdown have been calculaed snce Fro 1920 onwards a wholesale prce ndex has been repored onhly wh ore of a fxed srucure and a ore dealed produc group breakdown han was prevously he case. Ths se of sascs ook on s odern for n 1963 when a ore syseac nernaonal classfcaon of branches of econoc acvy was nroduced. 2 Observed varables The varables for whch he survey collecs prce daa are goods ransacons relang o Swedsh producers' sales of own-anufacured producs and goods pored no Sweden. 3 Sascal arges The producer and por prce ndces are desgned o easure on a onhly bass also whn dfferen produc groups he average prce developen n SEK of Swedsh-produced goods boh n overall ers and broken down no doesc arke and expors and pored goods. Ths se of sascs easures prce developen a he frs arkeng sage.e. doesc producers' sellng prces and porers' purchase prces respecvely. For Swedsh-anufacured goods he prce should be ex-works for he doesc arke and free on board (f.o.b) for expor sales. On he por sde prces should be c..f. (cos nsurance fregh). VAT and oher axes on goods are no aken no accoun. However here are wo excepons: he prce ndex for doesc supply (see below) whch s desgned o easure prce developen ncludng cusos dues and oher por axes (a presen however changes n cusos dues and oher por axes are no aken no accoun) as well as specfc ndex seres for peroleu producs whch nclude energy and envronenal axes. Any change of he prces charged/pad ha ses fro a change n qualy or oher prce-deernng characerscs should be adjused for. n prncple only pure prce changes ha are refleced n he prcng of coparable ransacons should have an pac on he prce ndex. The prce concerned s ha whch he purchaser acually pays afer deducon of any dscouns. Under Councl Regulaon (EC) o 1165/98 concernng shor-er sascs he ndex has o easure he developen of prces ncludng axes on goods (apar fro VAT) for orders receved durng he onh prarly on a ceran day n he onh. The Swedsh ndex however connues anly o

3 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 3(11) reflec he developen of he average prce for he onh's nvoces excludng axes on goods. 4 Objec and populaon The prce ndex a he producer and por sage s concerned wh ransacons. The populaon coprses respecvely all ransacons relang o sales a he producer sage and purchases a he por sage of producs belongng o he followng produc groups under rod-s197 (CA). Dvson Desgnaon A agrculural and foresry producs B fsh C producs fro nng and quarryng D ndusral producs E elecrcy gas heang and waer supply rod-s 97 s a classfcaon of producs based on acves fro he Swedsh Sandard ndusral Classfcaon S 1992 and uses he sae produc desgnaons as S 92 uses for correspondng acves. A furher objec used for saplng and daa collecon s enerprses. 5 Saplng and calculaon of weghs rce daa s colleced for a saple of ypcal ransacons. Hsorcally hs has been acheved by eans of he followng hree-sage approach: Frs all caegores exceedng a hreshold value were seleced. The saplng fraes used were (and sll are) Foregn rade sascs for he por- and Expor rce ndces and he annual sascs on roducon of coodes and ndusral servces (V) suppleened by soe addonal sources for he (doesc arke) roducer rce ndex. For he laer ndex he producon values are reduced by he correspondng expor values. Coody caegores accordng CA naonal ffh dg level exceedng 250 llon SEK (approx. 27 llon EUR) and C 8-dg level exceedng 350 llon SEK (38 llon EUR) where seleced. Whn CA he larges C caegory was seleced. Second he larges producers/porers (one or several) whn hose coody caegores were seleced. The selecon of enerprses was ade fro he sae source as he selecon of coody caegores. Thrd and fnally one or several ypcal ransacons (specfcaons) where seleced n consulaon wh he responden. Each year he saple s revsed and updaed parcularly n areas wh coody caegores of ncreasng porance. The saple s however no reexaned copleely. Therefore enerprses and e caegores ay rean n he saple alhough hey are no any longer aong he os poran ones. Each year also he respondens are asked o revew he specfcaons

4 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 4(11) and replace hose ha are no longer ypcal for he ransacons ade whn he caegory. As fro 2004 probably saplng are gradually replacng he frs wo sages: pars of enerprses and C 8-dg caegores are seleced whn CA sraa wh probables proporonal o her value. Sraa are defned accordng o CA ypcally a he 3-dg level. The nuber of observaons ade for pors expors and he doesc produce and sales are approxaely and 1500 respecvely. The observaons are suppled by a oal of 1200 enerprses. The weghs or he value aouns ha are used o aggregae sngle prce raos are allocaed fro he saple fraes accordng o he followng procedure: Whn a 5-dg CA (or soees 4-dg HS) all C 8-dg caegores receve equal weghs. Frs however any C 8-dg caegory ha s larger han or equal o he CA oal dvded by he nuber of C 8-dg caegores ncluded n he saple wll receve a wegh ha equals s share of he CA caegory. Hence relavely large C 8-dg caegores ay represen heselves only whereas saller caegores ncluded n he saple also represen hose oher sall caegores no ncluded n he saple. Before 2003 he dsrbuon of value weghs was proporonal o he value of each ncluded C 8-dg caegory; Whn C 8-dg caegores he values are dsrbued o producers/porers accordng o analogous prncples; Whn enerprses he values are dsrbued equally beween he specfcaons or accordng o any nforaon ha ay have been receved fro he responden. Exaple: Whn a caegory hree uns have been seleced represenng 40 9 and 1 per cen respecvely. Snce 40>100/3 he larges wll receve he wegh 40 whereas he res of he wegh wll be spl equally beween he oher wo (100-40)/230. Before 2003 he dsrbuon of value weghs whn CA caegores was proporonal o he value of hose C 8-dg caegores ncluded n he saple and whn C 8-dg caegores he dsrbuon was proporonal o he C 8-dg value of he producers/porers ncluded. Tha would have yelded he followng weghs: 40/(40+9+1)80 9/(40+9+1)18 and 1/(40+9+1)2 respecvely. Hence he new approach resuls n a ore evenly spread of he weghs whch s beleved o be ore effcen. The weghs are updaed annually as fro January each year based on year y-2 daa. n exceponal cases ore recen (han y-2) daa on values ay be used.

5 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 5(11) 6 Varables The an varable s he prce as descrbed above. The prce however can be repored n any currency. rces repored n foregn currency are hen convered no SEK. The nvoce currency and he reporng currency are herefore copleenary varables. Where prces are repored n foregn currences he Cusos and Excse Deparen's exchange raes are used for converng no SEK. These are based on he exchange rae on he hrd Wednesday of he onh precedng he easureen onh wh soe adjusen beng ade for exchange raes ha devae by ore han 5% whn he easureen onh. Ths ehod s used nsead of for exaple he Swedsh Cenral Bank's average exchange raes n order o prooe he usably of he ndex as a deflaor for esang expor and por values a consan prces n foregn rade sascs. Overall approxaely 15% of all expor prce daa and approxaely 25% of all por prce daa are provded n foregn currency whereas oher prces are n SEK. 7 ndex forulas The prce ndex a he producer and por sage can be descrbed as a Laspeyres-ype chan ndex wh annual lnks. A Laspeyres ndex s defned as Q Q ; k 0; k k 0; k 0; k 0 0; kq0; k k 0; kq0; k k k ; k 0; k where 0 and are he prce per un n he base perod (0) and he coparson perod () respecvely and Q 0 s he quany n he base perod. Suaon s across producs (ndcaed by k). n he cenre eleen above he ndex s expressed as he rao beween he suaed value of he baseperod quanes a he coparson-perod and base-perod prce level respecvely. The ndex can also be expressed as n he fnal eleen as an average of he goods' prce relaves weghed wh he base-perod values. The ndex lnks n he prce ndex a he producer and por sage are calculaed wh he curren onh n year y as he coparson perod and wh Deceber y-1 as prce reference perod. The weghng perod s he year y-2. A lnk s hus defned as: V y s y 1 dec s Vs s p p y ; s y1 dec; s where he value wegh Vs s he value of he ransacons n year y-2 ha are represened by he specfcaon s adjused by he esaed prce developen fro year y-2 o Deceber y-1

6 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 6(11) V y1 V s g. dec s y 2; s y2; g g s ypcally he C 8-dg caegory (Cobned oenclaure) conanng he seleced specfcaon. See secon 5 above "Saplng and calculaon of weghs" for a descrpon of how he value aouns V y-2;s are calculaed. 8 Reference perods The chaned ndex nuber s prarly calculaed for onhs and ndcaes he parcular onh's prce level copared wh he average prce level n 1990 ( ). 100 y1 y Y dec y 1990 Y 1 dec 1. DEC y dec M Y DEC M JA For he purpose of supplyng daa o Eurosa he ndex s also calculaed wh he base year ). As se ou above he ndex nuber anly reflecs he developen of an average prce for he onh. The annual average ndex s he unweghed arhecal ean of he onhly ndces.

7 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 7(11) Appendx 1: Qualy evaluaon Changes of he prces charged/pad ha are he resul of changed specfcaons regardng qualy or oher prce-deernng facors should no nfluence he prce ndex. Only pure prce changes ha are refleced n he prcng of coparable ransacons should have an pac on he prce coparson. n he prce ndex a he producer and por sages dsncons are ade beween he followng ypes of specfcaon changes. A new produc specfcaons: an explc evaluaon s ade n whch he new produc s gven a hgher value han he edae predecessor; C new produc specfcaons: an explc evaluaon s ade n whch he new produc s gven a lower value han he edae predecessor; E new produc specfcaons: an explc evaluaon s ade n whch he new produc s gven he sae value as he edae predecessor; new produc specfcaons whch resul erely n a change n volue or varey e.g. a nor change n he sze of he packagng; new produc specfcaons: overlap ehod appled by obanng he real basc prce for he new produc (for Deceber of he prevous year); K new produc specfcaons: overlap ehod appled by obanng he new produc's prce for he prevous onh; M produc no longer sold for res of year ndex pued fro oher aggregae; O new produc specfcaons: valuaon possble ndex assued o be unchanged fro prevous onh; R new produc specfcaons: valuaon possble ndex assued o be unchanged fro wo onhs earler or ore; T changed defnon of prce or prce calculaed on a dfferen bass fro prevously; Z oher. Calculaon of an adjused reference prce (prce as a Deceber of prevous year) n cases A and C a new basc prce s calculaed fro he qualy evaluaon ade n he parcular nsance. The queson arses here as o wha pac he change n specfcaons has had on he prce. The effec on prce can be gauged eher n ers of he changed specfcaons' pac on he cos of supplyng he produc or n ers of how he cusoer s expeced o apprase he change. A new reference prce (for onh ) s calculaed as ˆ ˆ F (1) where represens prces F he value of he change and he old and new produc respecvely and 0-1 and a parcular onh. 0 s hus he

8 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 8(11) reference onh. ˆ can be undersood as an esaed or pued prce for 1 he new produc n he prevous onh. Le us assue by way of exaple ha he prce for a produc n he orgnal specfcaons was SEK 38 n he reference onh (Deceber) ha he prce rose o SEK 40 n March and ha he prce for he produc accordng o he new specfcaons s SEK 45 n Aprl. Meeng he new specfcaons nvolves a greaer use of resources so ha he cos of supplyng he produc rses. The prce of SEK 45 s hus no coparable wh he reference-onh prce of SEK 38. Le us furher assue ha he change n specfcaons has led o a prce ncrease of SEK 3 per un. A new reference prce ha s coparable wh he prce for he new specfcaons can hus be calculaed as and he Aprl ndex (Dec 100) for hs quoaon can 40 hus be calculaed as n case a proporonal converson of he reference prce s carred ou. Case s sraghforward as he new reference prce s genune and can sply be subsued for he old one. ay be debaable however wheher he prevously recorded prce developen up o and ncludng he prevous onh should be superseded n hs way. The overlap case K requres ore careful reaen. Here he ndex has o be calculaed as (2) 0 0 wh he new pued reference prce beng correspondngly calculaed as (3) ˆ0 0 where represens prces and are he old and new producs respecvely and 0-1 and each represen a parcular onh. 0 s hus he reference onh. Le us say ha n he above exaple he produc eeng he new specfcaons was beng sold as early as March a a prce of SEK 44. A new basc prce ha s coparable wh he prce for he new specfcaons can hen be calculaed as The observed prce change n case M before he produc dsappeared should no be elnaed. Raher he ndex should n prncple be calculaed as

9 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 9(11) (4) A 0 0.e. puaon should be appled only for he e afer he produc's dsappearance. Where only he resuls up o and ncludng he onh before he curren onh can be used for puaon he las facor n he expresson A becoes he frs puaon onh equal o one ( 1 ). The os praccal procedure s now o nroduce a new "reference prce" (reference ndex) whch s he rao beween he aggregae's and he produc's ndex nuber for onh -1 as se ou below: A ˆ where (5) 0 Thereafer one sply nsers he ndex nuber for each new onh (Deceber 100) for he seres whch represens he ougong produc. Ths works because 1 A 0 0 (6) A A A 0 1 ˆ 0 Cases O and R are slar o case as far as he calculaon of he new basc prce s concerned. We can suarse he ndex calculaon as follows; s 0 (7) 0 f where s desgnaes he las onh wh he old specfcaon and f represens he frs onh wh he new one. The new pued reference prce s correspondngly calculaed as ˆ f (8) 0 0 s We noe ha n onh f whch s he new produc's frs observaon onh he ndex accordng o (7) s unchanged vs-à-vs onh -1. Qualy evaluaon of personal copuers (Cs) n order o adjus for specfcaon changes o personal copuers (por prce ndex) a so-called hedonc regresson odel s used (see J.Dalén 1989). The odel provdes esaes of paraeers for he hree varables RAM clock frequency and hard-dsk capacy whch are used o calculae he new basc prce.

10 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 10(11) M M MD F F F HD HD HD Y Bas Bas n Bas n Y e Z Z p p w p w p log log 1 1 log β β β e eperod RAM Clock frequency Hard dsk capacy M F HD The paraeers βˆ are esaed usng he leas square ehod n he usual way.

11 STATSTCS SWEDE July 2003 (rev 10 ay 2004) 11(11) Appendx 2: puaons The syse uses puaons for four dfferen ypes of non-response: - Copensaon for non-response: The prce does no coe n by he deadlne and s esaed usng he las prce o coe n whch s norally he prevous onh's prce. Ths s flagged and he nuber of puaons norally 1-3% of he saple s docuened each onh. - o ransacons: The prce s esaed usng he las-observed prce no flaggng. - roducs no longer sold: n cases where he copany has ceased radng or no longer pors/anufacures producs under he parcular arff headng he prce developen s pued usng he prce developen of closely relaed producs wh a one-onh e-lag. Ths s flagged and s docuened a year's end. orally 2-4% of he saple s pued usng hs ehod a he end of he year. - Larger produc groups no n he saple: Where easureens are copleely ssng for produc groups under rod-s 97 5-dg level wh values over SEK 250 llon or for a C headng wh values over SEK 350 llon hese are generally ncluded n he saple wh her weghs no grossed up o he prce reference onh level. The prce developen for hese s assued o be n lne wh ha of anoher closely relaed produc group whn whch prce easureens are carred ou or alernavely wh ha of he sae produc group on anoher arke (hoes sales expor por). The absence of easureens ay se for exaple fro he fac ha he group of goods concerned s characersed by unque or "alorade" producs. Ths eans ha s possble o easure prces for ransacons whch are coparable over e Anoher possble reason why he easureens ay be ssng s ha he bass for he weghng fgure or he saplng frae s clearly ou of dae n relaon o he new sascal year.