Formal definitions of field normalized citation indicators and their implementation at KTH Royal Institute of Technology

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1 orml deftos of feld ormlzed tto dtors d ther mplemetto t KTH Royl Isttute of Tehology Per Ahlgre d Peter Sjögårde, Itroduto Ths doumet desrbes the lulto of bblometr dtors bsed o feld ormlzto the bblometr dtbse t KTH (Bbmet), whh s bsed o Web of See dt. The dtors re desrbed Prt d spets regrdg mplemetto the KTH dtbse re ddressed Prt 2. The followg dtors re defed ths doumet: me feld ormlzed tto rte (f) top0% publtos (ptop0%) me feld ormlzed jourl mpt (jf) proporto publtos the 20% most frequetly ted jourls the feld (jtop20%) Prt Deftos Ths doumet trets the se, whh frtol outs re used the lultos of dtor vlues. I se whole outs should be used the lultos, Eq. () below s set to uty. Let A be ut of lyss, d the umber of publtos for A. Let r be the umber of uthors of the th publto for A. Let be the frto A hs of the th publto. We osder two ses. () A s orgzto. We tret two subses. (.) s the uthor frto A hs of the th publto d s defed s m å () rs j j where m s the umber of uthors fflted to A regrdg the th publto, d s j the umber of ffltos of the jth of these A uthors. Note tht the rght hd sde Eq. () s equl to m r whe eh A uthor hs extly oe fflto. (.2) s the orgzto frto A hs of the th publto d s defed s the umber of ourrees of A s me the ddress feld of the th publto dvded by the totl umber orgzto me ourrees the ddress feld questo. (2) A s dvdul uthor. s the uthor frto A hs of the th publto d s ths se defed s/ r.

2 . Me feld ormlzed tto rte We defe the me feld ormlzed tto rte for A, mf(a), s mf (A) å x å (2) ( ) q q x q å m q m q å mq j j mq å j j j where q ( ) s the umber of subjet tegores (the tto rte) of the th publto for A, m q s the umber of publtos, wth the sme publto yer d of the sme doumet type s the th publto for A, the qth subjet tegory of the th publto of A, d j ( j ) the tto rte of the jth of these publtos (the umber of subjet tegores of the jth of these publtos). µ q s the feld referee vlue tht the tto rte of the th publto,, s ormlzed gst regrdg the qth subjet tegory of the publto, d the ormlzto gves rse to feld ormlzed tto rte for the publto..2. ptop0% We defe ptop0% for A, ptop0%(a), s ptop0%(a) q b q q å å å (3) b + yq - q q + yq - yq q mx( mx(0.9, y ), 0) where q ( ) s the umber of subjet tegores (the tto rte) of the th publto for A, y ( q y + ) the proporto publtos wth respet to the tto dstrbuto, whh oers publtos wth the sme publto yer d of the sme doumet type s the th publto for A, d belogg to the qth subjet tegory of ths publto wth less th ( + ) ttos. q Weghts re used for the tto dstrbutos t stke. Eh tto vlue gve dstrbuto s ssged the weght /k, where k s the umber of subjet tegores of the orrespodg publto. The weght s the frto wth whh the publto otrbutes to eh of ts subjet tegores. The proporto publtos wth less th ttos s the the sum of the weghts for the tto vlues tht re less th, dvded by the sum of weghts for ll the tto vlues the dstrbuto. 2

3 + + q q q q mx( y -mx(0.9, y ),0) / y - y s the frto of the th publto wth whh the publto s ssged to the 0% most ted publtos. Observe tht ths frto s weghted by /q,.e., by the frto of the publto tht belogs to the qth subjet tegory. The pproh to ssg frtos of publtos to the (for ste) 0% most ted publtos s desrbed d dsussed by Wltm d Shreber (203)..3 Me feld ormlzed jourl mpt We defe the me feld ormlzed jourl mpt for A, mjf(a), s mjf (A) å å jf (4) jf p å j p x j ( ) j x å m j j q j jq m jq mjq k k mjq k å å k k where jf s the me feld ormlzed tto rte of the jourl, sy J, of the th publto, p the umber of publtos J, j the tto rte of the jth publto J, sy P j, j the umber of subjet tegores of P j, m jq the umber of publtos, wth the sme publto yer d of the sme doumet type s P j, the qth subjet tegory of P j, d k ( k ) the tto rte (the umber of subjet tegores) of the kth of these publtos. µ jq s the feld referee vlue tht the tto rte of P j, j, s ormlzed gst regrdg the qth subjet tegory of P j, d the ormlzto gves rse to feld ormlzed tto rte for P j (f. the defto of me feld ormlzed tto rte bove). (If J s o multdsplry jourl, j (j+) (j 0,,, p ), se the umber of subjet tegores of publto J s the equl to the umber of subjet tegores of J.) 2.4 Proporto publtos the 20% most frequetly ted jourls the feld We defe the proporto publtos the 20% most frequetly ted jourls the feld for A, jtop20%(a), s jtop20%(a) b q q å å å (5) 2 Cf. Seto 2.5 below. 3

4 b rq yq q rq rq - yq - yq rq - q mx(m(0.2, ) - y, 0) where s the umber of subjet tegores of the jourl, sy J, of the th publto of A, r q the rk of J the rkg of the jourls the qth subjet tegory of J, where the jourls re rked desedg fter ther me feld ormlzed tto rtes 3, y ( y r q q r q q - ) the proporto publtos pperg the jourls regrdg the rkg of the jourls the qth subjet tegory of J wth rk less th or equl to r q (r q ). 4 The rghtmost ftor b q s the frto of J wth whh J s ssged to the 20% most frequetly ted jourls the qth subjet tegory of J. Observe tht ths frto s weghted by /,.e., by the frto of J tht belogs to the qth subjet tegory. The pproh to ssg frtos of jourls to the (for ste) 20% most ted jourls s bslly the sme s the ssgmet pproh used the defto of ptop0% (Eq. (3)). Prt 2 Implemetto t KTH Royl Isttute of Tehology 2. Dtbse otets The bblometr dtbse t KTH (Bbmet) ots the followg dexes: See Ctto Idex Expeded (SCIE) Sol Sees Ctto Idex (SSCI) Arts & Humtes Ctto Idex (AHCI) Coferee Proeedgs Ctto Idex Sees (CPCI S) Coferee Proeedgs Ctto Idex Sol Sees & Humtes (CPCI SSH)). SCIE, SSCI, AHCI from 980 d CPCI S d CPCI SSH from Doumet types luded lultos I Bbmet, lultos re mde for ll ombtos of doumet types, publto yers d Web of See tegores. However, the defult presetto of feld ormlzed tto dtors oer oly rtles d revews. The reso for exludg other doumet types s the rsk for omles used by low umber of publtos the referee groups d questo mrks regrdg dt qulty d tto mthg (ths espelly pples to proeedgs ppers). 2.3 Cttos luded 3 Note tht for gve jourl the rkg, these rtes my vry ross the dfferet rkgs, orrespodg to dfferet subjet tegores, whh the jourl ours. 4 A o multdsplry jourl the rkg otrbutes, f eh of ts publtos hs feld referee vlue, wth respet to the qth subjet tegory of J, greter th or equl to 0.5 (see Seto 2 below), wth (/k)m publtos to the rkg, where k s the umber of subjet tegores of the jourl d m the umber of publtos of the jourl. 4

5 Cttos from ll reords the dtbse re luded the lultos. The dtors re lulted both wth self ttos luded d exluded. The defult presetto s mde wth selfttos exluded, se the teto whe lultg tto dtors s to see wht mpt publto hs hd o other reserhers th those who wrote the publto. urthermore, oe should vod gvg etves to systemt self quotto. 2.4 Retrotve hges of the Web of See subjet tegory ssged to jourls If jourl s relssfed from oe Web of See subjet tegory to other by Thomso Reuters (TR), o retrotve hges re mde the delvered rw dt. However, Web of See TR hges the lssfto retrotvely. Chges of the lssfto ffet the feld referee vlues d osequetly the outome of the lultos desrbed ths doumet. or Bbmet to be osstet wth Web of See, retrotve hges of the Web of See subjet tegores ssged to jourls re mde Bbmet. 2.5 Relssfto of jourls tegorzed s Multdsplry Web of See The lrge ( terms of publtos output) d hghly prestgous jourls Nture, See d PNAS re lssfed by TR s multdsplry. Whe feld ormlzto s ppled the lssfto of these hghly ted jourls to the sme tegory results very hgh feld referee vlues for ths "feld". By relssfyg publtos jourls wth the multdsplry subjet tegory ordg to ther "rel" tops the publtos re sted ompred to other publtos wth the sme subjet feld. The Swedsh Reserh Coul hs developed d ppled methodology for relssfto of publtos wth the multdsplry Web of See subjet tegory to other tegores bsed o ttos (Gursso, röberg, Jobsso, & Krlsso, 20). It ebles hgher degree of lke to lke omprso. The sme methodology s used t KTH. 2.6 Exluso of publto frtos wth low feld referee vlues or ll the four dtors defed Prt, publto frtos wth feld referee vlues less th 0.5 re exluded. 5 Exmple 2. (mf d ptop0%). Assume tht the th publto of A, sy P, belogs to three subjet tegores d tht extly oe of these tegores hs feld referee vlue less th 0.5 (regrdg publtos wth the sme publto yer d of the sme doumet type s P ). or Eq. (2), the deomtor d x the umertor re the multpled by 2/3, d q s equl to 2 (d ot to 3). Thus, the sum of x oers two feld ormlzed tto rtes for P, d the sum s multpled by /2 (d ot by /3). 5 Suh feld referee vlues mght gve rse to very lrge feld ormlzed tto rtes spte of few ttos. 5

6 or Eq. (3), uder the ssumptos gve, the deomtor d the rghtmost sum the umertor re multpled by 2/3, d q s equl to 2 (d ot to 3). Thus, the sum oers two rtos, both of whh re weghted by /2 (d ot by /3). Exmple 2.2 (mjf d jtop20%). Assume tht the jourl, J, of the th A publto belogs to four subjet tegores. Assume tht for the jth publto J, sy P j, publshed gve yer d of gve doumet type, two of the four subjet tegores hve feld referee vlue less th 0.5. or Eq. (4), 2/4 s subtrted from the deomtor of jf, d xj ts umertor s multpled by 2/4. j s equl to 2 (d ot to 4). Thus, the sum of xj oers two feld ormlzed tto rtes for P j, d the sum s multpled by /2 (d ot by /4). or jtop 20% (Eq. (5)), uder the ssumptos gve, two of the four rkgs whh J ours re suh tht P j does ot otrbute to the me feld ormlzed tto rtes of J the rkgs. Referees Gursso, M., röberg, J., Jobsso, C., & Krlsso, S. (20). Subjet lssfto of publtos the ISI dtbse bsed o referees d ttos (No. 4). Wltm, L., & Shreber, M. (203). O the lulto of peretle bsed bblometr dtors. Jourl of the Amer Soety for Iformto See d Tehology, 64(2),