chg6 - Phaàn 2 Phaàn 2 1- Khaùi nieäm: 1- Khaùi...

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Unformatted text preview: Phaàn 2 Phaàn 2 1- Khaùi nieäm: 1- Khaùi nieäm: Taäp hôïp taát caû caùc phaàn töû maø töø caùc phaàn töû ñoù ta coù theå khaûo saùt, thu thaäp nhöõng thoâng tin veà caùc daáu hieäu ta caàn nghieân cöùu ñöôïc goïi laø toång the å . Ki hieäu ́ N: soá phaàn töû cuûa toång theå ( kích thöôùc cuûa toång theå) X * : Daáu hieäu ta caàn khaûo saùt, nghieân cöùu (trong kinh teá thöôøng goïi laø chae tieâu). x i (i = 1, 2, ..., k) laø caùc giaù trò cuûa daáu hieäu X * ño ñöôïc treân caùc phaàn töû cuûa toång theå. N i (i = 1, 2, . . . , k): Taàn soá cuûa x i- laø soá phaàn töû nhaän giaù trò x i . ∑ = k 1 i i N p i (i = 1, 2, . . . , k): Taàn suaát cuûa x i N N i = N p i = Baûng cô caáu cuûa toång theå theo daáu hieäu X * Giaù trò cuûa X* x 1 x 2 . . . x k Taàn suaát (p i ) p 1 p 2 . . . p k 2- 2- Caùc soá ñaëc tröng Caùc soá ñaëc tröng cuûa toång theå: cuûa toång theå: 1- Trung bình cuûa toång theå 1- Trung bình cuûa toång theå μ = ∑ = k 1 i i i p . x 2- Phöông sai cuûa toång theå 2- Phöông sai cuûa toång theå σ 2 = ( 29 ∑ = μ- k 1 i i 2 i p x 3- Ñoä leäch chuaån cuûa toång 3- Ñoä leäch chuaån cuûa toång theå theå Ñoä leäch chuaån cuûa toång theå (kyù hieäu laø σ ) σ = 2 σ Giaû söû toång theå goàm N phaàn töû, trong ñoù coù M phaàn töû coù tính chaát A . Goïi p = laø tyû leä caùc phaàn töû coù tính chaát A cuûa toång theå (goïi taét laø N M N M 4- Tyû leä toång theå 4- Tyû leä toång theå Khaûo saùt chae tieâu X * : ” Thu nhaäp thöïc teá cuûa coâng nhaân ngaønh cao su ” vaø giaû söû thu ñöôïc caùc soá lieäu cho ôû Thí duï Thí duï : : Phöông sai cuûa thu nhaäp (phöông sai cuûa toång theå): σ 2 = (800 -1050) 2 *0,1 + + (900-1050) 2 *0,14 + +. . . + (1400-1050) 2 *0,05 = 23100 ª Ñoä leäch chuaån cuûa thu nhaäp (ñoä leäch chuaån cuûa toång theå): σ = = 151,987 151,987 23100 • Coù nhöõng tröôøng hôïp ta khoâng theå xaùc ñònh ñöôïc toaøn boä N phaàn töû cuûa toång theå. Töø toång theå ta laáy ra n phaàn töû vaø ño löôøng giaù trò cuûa daáu hieäu X * treân chuùng, n phaàn töû naøy laäp neân moät maãu. Soá phaàn töû cuûa maãu (n) ñöôïc goïi laø kích thöôùc maãu . Thoâng thöôøng kích thöôùc cuûa maãu nhoû hôn nhieàu so vôùi kích thöôùc cuûa toång theå. Söû duïng caùc phöông phaùp toaùn hoïc ngöôøi ta tieán haønh suy roäng keát quaû nghieân cöùu treân maãu cho toaøn boä toång theå, ñoù laø muïc ñích cuoái cuøng cuûa phöông phaùp maãu. Ñeå ñaït ñöôïc muïc ñích treân...
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This note was uploaded on 06/14/2010 for the course ACCOUNTING 123456 taught by Professor Vananh during the Spring '10 term at Vaasan ammattikorkeakoulu.

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chg6 - Phaàn 2 Phaàn 2 1- Khaùi nieäm: 1- Khaùi...

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