Répartition optimale pour une enquête téléphonique à base de sondage double 3. Protocole de présélection

Dans le protocole de présélection, on procède à l’interview de toutes les unités de l’échantillon de lignes fixes s A . MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGaam4CamaaBa aaleaacaWGbbaabeaakiaac6caaaa@39B2@ On réalise une interview de présélection auprès de toutes les unités de l’échantillon de lignes mobiles s B MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGaam4CamaaBa aaleaacaWGcbaabeaaaaa@38F7@ (pour déterminer la situation d’usage du téléphone), puis on effectue l’interview de l’enquête uniquement auprès des unités retenues comme étant EXM. Par conséquent, les coûts attendus de la collecte des données suivent le modèle :

C S C = c A n A + c B β n B + c B ( 1 β ) n B = c A n A + c B n B , ( 3.1 ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qafaqaaeGacaaabaGaam4qa8aadaWgaaWcbaWdbiaadofacaWGdbaa paqabaaak8qabaGaeyypa0Jaam4ya8aadaWgaaWcbaWdbiaadgeaa8 aabeaak8qacaWGUbWdamaaBaaaleaapeGaamyqaaWdaeqaaOWdbiab gUcaRiqadogagaqbamaaBaaaleaacaWGcbaabeaakiabek7aIjaad6 gapaWaaSbaaSqaa8qacaWGcbaapaqabaGcpeGaey4kaSIabm4yayaa gaWaaSbaaSqaaiaadkeaaeqaaOWaaeWaa8aabaWdbiaaigdacqGHsi slcqaHYoGyaiaawIcacaGLPaaacaWGUbWdamaaBaaaleaapeGaamOq aaWdaeqaaaGcpeqaaaqaaiabg2da9iaadogapaWaaSbaaSqaa8qaca WGbbaapaqabaGcpeGaamOBa8aadaWgaaWcbaWdbiaadgeaa8aabeaa k8qacqGHRaWkceWGJbGbaibadaWgaaWcbaGaamOqaaqabaGccaWGUb WdamaaBaaaleaapeGaamOqaaWdaeqaaOWdbiaacYcaaaWdaiaaywW7 caaMf8UaaGzbVlaaywW7caaMf8UaaiikaiaaiodacaGGUaGaaGymai aacMcaaaa@666D@

c B MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qaceWGJbGbauaadaWgaaWcbaGaamOqaaqabaaaaa@3913@ est le coût de l’interview de présélection d’une unité de l’échantillon s B MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGaam4CamaaBa aaleaacaWGcbaabeaaaaa@38F7@ (en vue de déterminer sa situation d’usage du téléphone), c B MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGabm4yayaaga WaaSbaaSqaaiaadkeaaeqaaaaa@38F4@ est le coût de l’interview de présélection et de l’interview d’enquête d’une unité de l’échantillon s B MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGaam4CamaaBa aaleaacaWGcbaabeaaaaa@38F7@ et c B = c B β + c B ( 1 β ) . MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qaceWGJbGbaibadaWgaaWcbaGaamOqaaqabaGccqGH9aqpceWGJbGb auaadaWgaaWcbaGaamOqaaqabaGccqaHYoGycqGHRaWkceWGJbGbay aadaWgaaWcbaGaamOqaaqabaGcdaqadaWdaeaapeGaaGymaiabgkHi Tiabek7aIbGaayjkaiaawMcaaiaac6caaaa@463B@ Dans cette notation, n A MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWGUbWdamaaBaaaleaapeGaamyqaaWdaeqaaaaa@393F@ est le nombre d’interviews d’enquête achevées auprès des répondants de l’échantillon de lignes fixes et n B MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWGUbWdamaaBaaaleaapeGaamOqaaWdaeqaaaaa@3940@ est le nombre d’interviews achevées (interview de présélection seulement pour les répondants non EXM, et interviews de présélection et d’enquête pour les répondants EXM) auprès des répondants de l’échantillon de lignes mobiles. Cela veut dire que le nombre espéré d’interviews d’enquête achevées est n A + ( 1 β ) n B . MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWGUbWdamaaBaaaleaapeGaamyqaaWdaeqaaOWdbiabgUcaRmaa bmaapaqaa8qacaaIXaGaeyOeI0IaeqOSdigacaGLOaGaayzkaaGaam OBa8aadaWgaaWcbaWdbiaadkeaa8aabeaakiaac6caaaa@41FE@

L’estimateur sans biais du total pour l’ensemble de la population est :

Y ^ = Y ^ A + Y ^ b   , ( 3.2 ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGabmywayaaja aeaaaaaaaaa8qacqGH9aqppaGabmywayaajaWaaSbaaSqaa8qacaWG bbaapaqabaGcpeGaey4kaSYdaiqadMfagaqcamaaBaaaleaapeGaam OyaaWdaeqaaOWdbiaabckacaGGSaGaaGzbVlaaywW7caaMf8UaaGzb VlaaywW7caGGOaGaaG4maiaac6cacaaIYaGaaiykaaaa@4B8F@

Y ^ A = ( N A / n A ) y A , MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGabmywayaaja WaaSbaaSqaaabaaaaaaaaapeGaamyqaaWdaeqaaOWdbiabg2da9maa bmaapaqaa8qadaWcgaqaaiaad6eapaWaaSbaaSqaa8qacaWGbbaapa qabaaak8qabaGaamOBa8aadaWgaaWcbaWdbiaadgeaa8aabeaaaaaa k8qacaGLOaGaayzkaaGaamyEa8aadaWgaaWcbaWdbiaadgeaa8aabe aakiaacYcaaaa@430B@ Y ^ b = ( N B / n B ) y b , MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaGabmywayaaja WaaSbaaSqaaabaaaaaaaaapeGaamOyaaWdaeqaaOWdbiabg2da9maa bmaapaqaa8qadaWcgaqaaiaad6eapaWaaSbaaSqaa8qacaWGcbaapa qabaaak8qabaGaamOBa8aadaWgaaWcbaWdbiaadkeaa8aabeaaaaaa k8qacaGLOaGaayzkaaGaamyEa8aadaWgaaWcbaWdbiaadkgaa8aabe aakiaacYcaaaa@434F@ et y A = y a + y a b . MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWG5bWdamaaBaaaleaapeGaamyqaaWdaeqaaOWdbiabg2da9iaa dMhapaWaaSbaaSqaa8qacaWGHbaapaqabaGcpeGaey4kaSIaamyEa8 aadaWgaaWcbaWdbiaadggacaWGIbaapaqabaGccaGGUaaaaa@4185@ La variance de cet estimateur est :

Var { Y ^ } = N 2 ( R A 2 n A + R B 2 n B )   , ( 3.3 ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaqGwbGaaeyyaiaabkhadaGadaWdaeaaceWGzbGbaKaaa8qacaGL 7bGaayzFaaGaeyypa0JaamOta8aadaahaaWcbeqaa8qacaaIYaaaaO WaaeWaa8aabaWdbmaalaaapaqaa8qacaWGsbWdamaaDaaaleaapeGa amyqaaWdaeaapeGaaGOmaaaaaOWdaeaapeGaamOBa8aadaWgaaWcba Wdbiaadgeaa8aabeaaaaGcpeGaey4kaSYaaSaaa8aabaWdbiaadkfa paWaa0baaSqaa8qacaWGcbaapaqaa8qacaaIYaaaaaGcpaqaa8qaca WGUbWdamaaBaaaleaapeGaamOqaaWdaeqaaaaaaOWdbiaawIcacaGL PaaacaGGGcGaaiilaiaaywW7caaMf8UaaGzbVlaaywW7caaMf8Uaai ikaiaaiodacaGGUaGaaG4maiaacMcaaaa@5A43@

R A 2 = W A 2 S A 2 MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWGsbWdamaaDaaaleaapeGaamyqaaWdaeaapeGaaGOmaaaakiab g2da9iaadEfapaWaa0baaSqaa8qacaWGbbaapaqaa8qacaaIYaaaaO Gaam4ua8aadaqhaaWcbaWdbiaadgeaa8aabaWdbiaaikdaaaaaaa@4097@

et

R B 2 = W B 2 S b 2 { 1 β + β ( 1 β ) Y ¯ b 2 S b 2 }   . MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWGsbWdamaaDaaaleaapeGaamOqaaWdaeaapeGaaGOmaaaakiab g2da9iaadEfapaWaa0baaSqaa8qacaWGcbaapaqaa8qacaaIYaaaaO Gaam4ua8aadaqhaaWcbaWdbiaadkgaa8aabaWdbiaaikdaaaGcdaGa daWdaeaapeGaaGymaiabgkHiTiabek7aIjabgUcaRiabek7aInaabm aapaqaa8qacaaIXaGaeyOeI0IaeqOSdigacaGLOaGaayzkaaWaaSaa a8aabaGabmywayaaraWaa0baaSqaa8qacaWGIbaapaqaa8qacaaIYa aaaaGcpaqaa8qacaWGtbWdamaaDaaaleaapeGaamOyaaWdaeaapeGa aGOmaaaaaaaakiaawUhacaGL9baacaGGGcGaaiOlaaaa@55D6@

La répartition optimale de l’échantillon total est :

n A, opt = L R A / c A n B, opt = L R B / c B , MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaqbaeaabiWaaa qaaabaaaaaaaaapeGaamOBa8aadaWgaaWcbaWdbiaadgeacaGGSaGa aeiOaiaad+gacaWGWbGaamiDaaWdaeqaaaGcbaGaeyypa0dabaWdbm aalyaabaGaamitaiaadkfapaWaaSbaaSqaa8qacaWGbbaapaqabaaa k8qabaWaaOaaa8aabaWdbiaadogapaWaaSbaaSqaa8qacaWGbbaapa qabaaapeqabaaaaaGcpaqaa8qacaWGUbWdamaaBaaaleaapeGaamOq aiaacYcacaqGGcGaam4BaiaadchacaWG0baapaqabaaakeaacqGH9a qpaeaapeWaaSGbaeaacaWGmbGaamOua8aadaWgaaWcbaWdbiaadkea a8aabeaaaOWdbeaadaGcaaWdaeaapeGabm4yayaasaWaaSbaaSqaai aadkeaaeqaaaqabaaaaOGaaiilaaaaaaa@524C@

L   MathType@MTEF@5@5@+= feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qacaWGmbGaaiiOaaaa@3921@ est une constante qui dépend de la contrainte retenue : contrainte de coût ou de variance. La variance minimale à coût total fixe est :

min [ Var { Y ^ } ] = ( c A R A + c B R B ) 2 C S C   , ( 3.4 ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiFu0Je9sqqrpepC0xbbL8F4rqqrpipeea0xe9Lq=Je9 vqaqFeFr0xbbG8FaYPYRWFb9fi0FXxbbf9=e0dfrpm0dXdHqVu0=vr 0=vr0=fdbaqaaeGacaGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 qaciGGTbGaaiyAaiaac6gadaWadaWdaeaapeGaciOvaiaacggacaGG YbWaaiWaa8aabaGabmywayaajaaapeGaay5Eaiaaw2haaaGaay5wai aaw2faaiabg2da9maalaaapaqaa8qadaqadaWdaeaapeWaaOaaa8aa baWdbiaadogapaWaaSbaaSqaa8qacaWGbbaapaqabaaapeqabaGcca WGsbWdamaaBaaaleaapeGaamyqaaWdaeqaaOWdbiabgUcaRmaakaaa paqaa8qaceWGJbGbaibadaWgaaWcbaGaamOqaaqabaaabeaakiaadk fapaWaaSbaaSqaa8qacaWGcbaapaqabaaak8qacaGLOaGaayzkaaWd amaaCaaaleqabaWdbiaaikdaaaaak8aabaWdbiaadoeapaWaaSbaaS qaa8qacaWGtbGaam4qaaWdaeqaaaaakmaaBaaaleaapeGaaeiOaaWd aeqaaOGaaiilaiaaywW7caaMf8UaaGzbVlaaywW7caaMf8Uaaiikai aaiodacaGGUaGaaGinaiaacMcaaaa@5FD4@

et le coût minimal à variance fixe est :

min [ C S C ] = ( c A R A + c B R B ) 2 V 0   . ( 3.5 )

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