Teoria de Amostragem

 

Bmsmgvfjvhemgtf A aefstrakme m me parthiujar fs prfimssfs bm aefstrakme apjhiae-sm me varhabåssheas ármas bf ifg`mihemgtf m ifgsthtume, euhtas vmzms, a ôghia nfrea bm fotmr hgnfreaëýms sform uea bmtmrehgaba rmajhbabm qum hepfrta ifg`mimr. A tmfrha ba aefstrakme ²m asshe ue bfs hgstruemgtfs qum pfsshohjhta mssm ifg`mihemgtf ihmgtånhif ba rmajhbabm, fgbm futrfs prfimssfs fu eètfbfs ajtmrgathvfs, pfr razýms bhvmrsas, géf sm efstrae abmquabfs fu atè emsef pfssåvmhs.  A tmfrha ba aefstrakme mstuba as rmjaëýms mxhstmgtms mgtrm uea pfpujaëéf m as aefstras mxtraåbas bmssa pfpujaëéf. È ôthj para avajhaëéf bm kragbmzas ² bmsifg`mihbas ba pfpujaëéf, fu para bmtmrehgar sm as bhnmrmgëas fosmrvabas mgtrm buas aefstras séf bmvhbas af aiasf fu sm séf vmrbabmhraemgtm shkghnhiathvas. Aefstrakme ²m f prfimssf bm bmtmrehgaëéf bm uea aefs ae fstra tra a smr smr pmsq pmsquh uhsa saba ba.. A ae aefs fstr traa ²m ue ueaa pa part rtmm bm mj mjme memg mgtf tfss sm smjm jmih ihfg fgab abaa bm uea uea  pfpujaëéf mstatåsthia. mstatåsthia. Mgquagtf qum ue smgsf mgvfjvm ue mxaem a tfbfs fs mjmemgtfs bm ue babf krupf, a aefstrakme mgvfjvm ue mstubf bm apmgas uea partm bfs mjmemgtfs. A aefstrakme ifgshstm me smjmiihfgar partm bm uea pfpujaëéf m fosmrvá-ja ife vhsta a msthear uea fu eahs iaraitmråsthias para a tftajhbabm ba pfpujaëéf. Ajkugs mxmepjfs ba uthjhzaëéf ba aefstrakme séf4

Yfgbakmgs la fphghéf pôojhia qum smrvme para ifg`mimr a fphghéf ba pfpujaëéf sform varhabas qumstýms. As eahs pfpujarms séf as sfgbakmgs pfjåthias3 Hgspmëéf bm emriabf uthjhzaba ife f hgtuhtf bm bmsiforhr as prmnmrägihas bas pmssfas me rmjaëéf a imrtfs prfbutfs. ]e bfs mxmepjfs eahs ifg`mihbfs ba apjhiaëéf bmsta aefstrakme ²m a jhsta bm aubhägihas bfs prfkraeas bm tmjmvhséf. Fs tmrefs oáshifs me aefstrakme séf4

\fpujaëéf - f krupf hgtmhrf bm fodmitfs (ughbabms) bfs quahs sm prmtmgbm fotmr  hgnfreaëýms. A pfpujaëéf bmvm smr bmnhghba ijaraemgtm m me tmrefs baquhjf qum sm  prmtmgbm ifg`mimr3 ifg`mimr3 ]ghbabm - quajqumr mjmemgtf hgbhvhbuaj ba pfpujaëéf3 Aefstra - uea partm fu suoifgdugtf ba pfpujaëéf usaba para fotmr hgnfreaëéf aimria bf tfbf.

 

As nasms bm ue prfimssf bm aefstrakme

Bmpfhs bm sm hbmgthnhiar fs babfs qum bmvmréf smr rmifj`hbfs m f hgstruemgtf (qumsthfgárhf mstruturabf, pfr mxmepjf) a uthjhzar para mssa rmifj`a, f passf smkuhgtm ifgshstm me bmnhghr  ue prfimssf bm aefstrakme abmquabf af thpf bm babfs m af hgstruemgtf bm agájhsm.  Gf prfimssf bm rmifj`a bm babfs è gmimssárhf bmsmgvfjvmr ue prfimssf shs- tmeáthif qum assmkurm a nhaohjhbabm m ifeparaohjhbabm bmssms babfs. Eahs mspmihnhiaemgtm, è gmimssárhf qum sm mstaomjmëa á parthba ue pjagf bm aefstrakme bm aifrbf ife a pfpujaëéf ajvf, ife a bmnhg bmnhghëé hëéff ba pfpuja pfpujaëéf ëéf a hgq hgquhr uhrhr hr m if ife e ue prf prfims imssf sf abm abmqua quabf bf bm ab abehg ehghst hstraë raëéf éf bf hgquèrhtf. F pjagf bm aefstrakme bmvmrá ifemëar pfr bmtmrehgar quaj f g²gåvmj bm mxtmgséf kmfkránhia me qum f prfimssf bm aefstrakme bmvmrá smr ifgbuzhbf (eugbhaj, gaihfgaj, rmkhfgaj, uroagf, ruraj, krupf bm hgbhvåbufs, mti.). A ifgstruëéf ba aefstra prfprhaemgtm bhta mgvfjvm várhas mtapas hkuajemgtm hepfrtagtms m qum séf4 A hbmgthnhiaëéf ba pfpujaëéf ajvf/pfpujaëéf ajvf/pfpujaëéf hgquhrhba3 F eètfbf bm smjmiëéf ba aefstra3 A bhemgséf ba aefstra. Eètfbfs bm aefstrakme ajmatùrha4 Aefstrakme ajmatùrha shepjms

]ea aefstra ajmatùrha shepjms bm g mjmemgtfs bm uea pfpujaëéf bm g mjmemgtfs m ue suoifgdugtf bm g mjmemgtfs bhsthgtfs ba pfpujaëéf, mxtraåbfs bm efbf qum quajqumr bas ( Nfreuja

 G  g

) aefstras pfssåvmhs tme hkuaj

 

Aefstrakme Ajmatùrha Mstrathnhiaba

\rhemhraemgtm a pfpujaëéf ( G  suopfpujaëýms ms (mstratfs) ife  G 11,, G ?, ?, ..., GJ  G ) è bhvhbhba me J suopfpujaëý mjme mjmemg mgtf tfs. s. \a \ara ra ia iaba ba ms mstr trat atf, f, ms msif ifj` j`m-s m-smm gh mjm mjmemg emgtfs tfs ajmatf ajmatfrhae rhaemgt mgtm, m, tftajh tftajhza zagbf gbf g mjmemgtfs. Nfreujas gh

g

 5  J  

gh 5 g

 G h  G 

g h 5g

 

 G h Yh  J

∑  G   Yh h

h 5j

Rfbfs hkuahs varhaohjhbabm)

prfpfrihfgahs a  G h

taeag`f ùthef (ifgshbmra a

A aefstrakme shstmeáthia

È ue thpf bm aefstrakme prfoaohjåsthia, fgbm sm naz uea smjmëéf ajmatùrha bf prhemhrf mjmemgtf para a aefstra m jfkf sm smjmihfgae fs htmgs suosmqumgtms uthjhzagbf hgtmrvajfs nhxfs fu shstmeáthifs atè i`mkar af taeag`f ba aefstra bmsmdaba.