Qhov tsis muaj nuj nqis hauv cov kev txheeb cais yog cov ntsuas dav dav uas qhia qhov sib txawv ntawm qhov tshwm sim hauv kev tshwj xeeb ntawm qhov chaw thiab sijhawm. Qhov loj tsis txaus yog nws tus nqi coj los ntawm nws tus kheej tsis hais txog qhov loj ntawm lwm yam tshwm sim. Qhov tsis tseem ceeb yog cov naj npawb npe uas nthuav tawm qhov loj ntawm qhov tshwm sim hauv qee qhov kev ntsuas ntawm kev ntsuas (neeg, rubles, tej daim, neeg-hnub, thiab lwm yam). Qhov kev loj hlob tsis tseeb yog hais txog qhov ntsuas ntawm cov kab ua ntu zus. Cov lej ntawm qhov muaj zog (cov sijhawm) yog cov ntu ntawm cov naj npawb raws li ntsuas uas txawv txav ntawm cov xwm txheej dhau los.
Nws yog qhov tsim nyog
Lub laij lej, cov ntaub ntawv ntawm kev hloov pauv ntawm ntau lawm kev lag luam ntawm cov khoom lag luam txheeb xyuas
Cov Lus Qhia
Kauj ruam 1
Txheeb xyuas qhov tsis txaus ntawm qhov nce qib ntawm qhov pib raws li qhov sib txawv ntawm qhov tam sim no thiab theem pib ntawm cov koob uas siv tus qauv:
Δi = yi - yo, qhov twg yi yog qib tam sim no ntawm cov kab, yo yog pib theem ntawm kab.
Piv txwv:
Xyoo 1997, cov khoom tsim tawm rau 10 lab tons, xyoo 1998 - 12 lab tons, xyoo 1999 - 16 lab tons, xyoo 2000 - 14 lab tons.
I = 12 - 10 = 2 lab tons
I = 16 - 10 = 6 lab tons
I = 14 - 10 = 4 lab tons
Kauj ruam 2
Txheeb xyuas qhov nce qhov loj txaus ntawm ib txoj saw txuas raws qhov sib txawv ntawm qhov tam sim no thiab qib theem ntawm cov koob uas siv tus qauv:
Δi = yi - yi-1, qhov twg yi yog qib tam sim no ntawm cov kab, yi-1 yog qib dhau los ntawm kab.
Piv txwv:
Xyoo 1997, cov khoom tsim tawm rau 10 lab tons, xyoo 1998 - 12 lab tons, xyoo 1999 - 16 lab tons, xyoo 2000 - 14 lab tons.
I = 12 - 10 = 2 lab tons
I = 16 - 12 = 4 lab tons
I = 14 - 16 = -2 lab tons
Kauj ruam 3
Laij ntsuas qhov nruab nrab qhov loj me qia nruab nrab siv tus qauv:
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= Yn - y1 / n-1, qhov twg y1 yog thawj theem ntawm kab, n yog najnpawb ntawm cov theem nyob rau hauv kab, yn yog kawg theem ntawm kab.
Piv txwv:
Xyoo 1997, cov khoom lag luam tsim tawm rau 10 lab tons, xyoo 1998 - 12 lab tons, xyoo 1999 - 16 lab tons, xyoo 2000 - 14 lab tons.
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= 14-10 / 4-1 = 1.3 lab tons
