Dispersion vs Skewness
Nyob rau hauv kev txheeb cais thiab qhov tshwm sim txoj kev xav, feem ntau qhov kev hloov pauv hauv kev faib khoom yuav tsum tau nthuav tawm ntau yam rau lub hom phiaj ntawm kev sib piv. Dispersion thiab Skewness yog ob lub ntsiab lus kev txheeb cais uas cov duab ntawm kev faib khoom nthuav tawm hauv qhov ntsuas ntau.
Ntau txog Dispersion
Hauv kev txheeb cais, qhov kev sib cais yog qhov hloov pauv ntawm qhov sib txawv ntawm qhov sib txawv lossis nws qhov yuav tshwm sim. Nws yog ib qho kev ntsuas ntawm qhov deb npaum li cas cov ntaub ntawv cov ntsiab lus nyob ntawm tus nqi nruab nrab. Txhawm rau nthuav tawm qhov ntau npaum li cas, kev ntsuas ntawm kev sib cais yog siv rau hauv cov ntaub ntawv piav qhia.
Variance, Standard Deviation, thiab Inter-quartile ntau yam yog cov feem ntau siv ntsuas ntawm dispersion.
Yog tias cov ntaub ntawv muaj nuj nqis muaj ib chav tsev, vim yog qhov ntsuas, qhov ntsuas ntawm kev sib cais kuj tseem muaj tib chav. Interdecile ntau yam, Range, qhov sib txawv, qhov nruab nrab qhov sib txawv ntawm qhov nruab nrab, qhov nruab nrab qhov sib txawv ntawm qhov sib txawv, thiab qhov sib txawv ntawm qhov sib txawv yog ntsuas ntawm qhov sib txawv nrog cov units.
Hauv qhov sib piv, muaj kev ntsuas ntawm kev sib cais uas tsis muaj units, piv txwv li tsis muaj qhov dav. Variance, Coefficient ntawm variation, Quartile coefficient ntawm dispersion, thiab txheeb ze txhais tau tias sib txawv yog ntsuas ntawm dispersion tsis muaj units.
Kev sib cais hauv ib qho system tuaj yeem tshwm sim los ntawm qhov yuam kev, xws li ntsuas ntsuas thiab ntsuas qhov yuam kev. Tsis tas li ntawd, kev hloov pauv hauv qhov qauv nws tus kheej tuaj yeem ua rau muaj kev hloov pauv. Nws yog ib qho tseem ceeb kom muaj lub tswv yim ntau txog qhov sib txawv ntawm cov ntaub ntawv ua ntej ua lwm yam kev txiav txim siab los ntawm cov ntaub ntawv teev.
Ntau txog Skewness
Hauv kev txheeb cais, skewness yog ib qho kev ntsuas ntawm asymmetry ntawm qhov yuav tshwm sim. Skewness tuaj yeem yog qhov zoo lossis tsis zoo, lossis qee qhov tsis muaj nyob. Nws kuj tseem tuaj yeem suav tias yog qhov ntsuas ntawm offset los ntawm kev faib tawm ib txwm.
Yog tias qhov skewness yog qhov zoo, ces cov ntaub ntawv feem ntau yog nyob rau sab laug ntawm txoj kab nkhaus thiab sab xis yog ntev dua. Yog tias qhov skewness tsis zoo, feem ntau ntawm cov ntaub ntawv cov ntsiab lus yog nyob rau sab xis ntawm txoj kab nkhaus thiab sab laug tus Tsov tus tw yog qhov ntev. Yog tias qhov skewness yog xoom, ces cov pejxeem feem ntau faib.
Nyob rau hauv ib txwm faib, uas yog thaum lub nkhaus yog symmetric, qhov nruab nrab, nruab nrab, thiab hom muaj tib yam nqi. Yog tias qhov skewness tsis yog xoom, cov cuab yeej no tsis tuav, thiab qhov nruab nrab, hom, thiab nruab nrab yuav muaj qhov sib txawv.
Pearson thawj thiab thib ob coefficients ntawm skewness feem ntau yog siv los txiav txim qhov skewness ntawm kev faib khoom.
Pearson thawj skewness coffeicent=(txhais tau tias - hom) / (tus qauv sib txawv)
Pearson tus thib ob skewness coffeicent=3(txhais tau tias - hom) / (satndard deviation)
Nyob rau hauv cov ntaub ntawv rhiab ntau, kho Fisher-Pearson tus qauv lub sijhawm coefficient yog siv.
G={n / (n-1)(n-2)} ∑i=1 ((y-ӯ)/s)3
Dab tsi yog qhov txawv ntawm Dispersion thiab Skewness?
Kev txhawj xeeb txog kev txhawj xeeb txog qhov ntau ntawm cov ntaub ntawv cov ntsiab lus raug faib, thiab qhov skewness txhawj xeeb txog qhov sib luag ntawm kev faib khoom.
Ob qhov kev ntsuas ntawm kev tawg thiab skewness yog piav qhia kev ntsuas thiab coefficient ntawm skewness muab ib qho kev qhia rau cov duab ntawm kev faib.
Kev ntsuas ntawm kev tawg yog siv los nkag siab txog ntau yam ntawm cov ntaub ntawv cov ntsiab lus thiab offset los ntawm qhov txhais tau tias thaum skewness yog siv los nkag siab qhov nyiam ntawm qhov sib txawv ntawm cov ntaub ntawv cov ntsiab lus rau hauv ib qho kev taw qhia.
