{"id":26100,"date":"2023-12-07T02:23:04","date_gmt":"2023-12-07T02:23:04","guid":{"rendered":"https:\/\/masterskills.org\/blog\/kiem-dinh-z-z-test-la-gi-cach-thuc-hoat-dong-cua-kiem-dinh-z.html"},"modified":"2023-12-22T11:27:13","modified_gmt":"2023-12-22T04:27:13","slug":"kiem-dinh-z-z-test-la-gi-cach-thuc-hoat-dong-cua-kiem-dinh-z","status":"publish","type":"post","link":"https:\/\/masterskills.org\/blog\/kiem-dinh-z-z-test-la-gi-cach-thuc-hoat-dong-cua-kiem-dinh-z.html","title":{"rendered":"Ki\u1ec3m \u0111\u1ecbnh Z (Z-Test) l\u00e0 g\u00ec? C\u00e1ch th\u1ee9c ho\u1ea1t \u0111\u1ed9ng c\u1ee7a ki\u1ec3m \u0111\u1ecbnh Z"},"content":{"rendered":"
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Hi\u0300nh minh ho\u0323a. Ngu\u00f4\u0300n: Youtube.com<\/i><\/p>\n<\/div>\n<\/div>\n

Ki\u1ec3m \u0111\u1ecbnh Z<\/font><\/h2>\n

Kha\u0301i ni\u00ea\u0323m<\/b><\/p>\n

Ki\u1ec3m \u0111\u1ecbnh Z<\/b> trong ti\u00ea\u0301ng Anh la\u0300 Z-Test<\/b>.<\/p>\n

Ki\u1ec3m \u0111\u1ecbnh Z <\/b>l\u00e0 m\u1ed9t h\u00ecnh th\u1ee9c ki\u1ec3m \u0111\u1ecbnh th\u1ed1ng k\u00ea \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh xem hai gi\u00e1 tr\u1ecb trung b\u00ecnh t\u1ed5ng th\u1ec3 c\u00f3 kh\u00e1c nhau hay kh\u00f4ng khi bi\u1ebft c\u00e1c ph\u01b0\u01a1ng sai v\u00e0 k\u00edch th\u01b0\u1edbc m\u1eabu l\u1edbn.<\/p>\n

Th\u1ed1ng k\u00ea \u0111\u01b0\u1ee3c ki\u1ec3m \u0111\u1ecbnh ph\u1ea3i c\u00f3 gi\u1ea3 \u0111\u1ecbnh l\u00e0 ph\u00e2n ph\u1ed1i chu\u1ea9n v\u00e0 c\u00e1c tham s\u1ed1 nh\u01b0\u00a0\u0111\u1ed9 l\u1ec7ch chu\u1ea9n\u00a0ph\u1ea3i \u0111\u01b0\u1ee3c bi\u1ebft tr\u01b0\u1edbc \u0111\u1ec3 th\u1ef1c hi\u1ec7n ki\u1ec3m \u0111\u1ecbnh Z<\/b> m\u1ed9t c\u00e1ch ch\u00ednh x\u00e1c.<\/p>\n

Gi\u00e1 tr\u1ecb th\u1ed1ng k\u00ea z, hay\u00a0z-score\u00a0(\u0111i\u1ec3m z) l\u00e0 m\u1ed9t con s\u1ed1 bi\u1ec3u th\u1ecb c\u00f3 bao nhi\u00eau \u0111\u1ed9 l\u1ec7ch chu\u1ea9n \u1edf tr\u00ean ho\u1eb7c d\u01b0\u1edbi trung b\u00ecnh t\u1ed5ng th\u1ec3. L\u00e0 m\u1ed9t gi\u00e1 tr\u1ecb c\u00f3 \u0111\u01b0\u1ee3c t\u1eeb ki\u1ec3m \u0111\u1ecbnh Z.<\/p>\n

C\u00e1ch th\u1ee9c ho\u1ea1t \u0111\u1ed9ng c\u1ee7a Ki\u1ec3m \u0111\u1ecbnh Z<\/font><\/h3>\n

C\u00e1c ki\u1ec3m \u0111\u1ecbnh c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n b\u1edfi ki\u1ec3m \u0111\u1ecbnh Z<\/b> bao g\u1ed3m ki\u1ec3m \u0111\u1ecbnh v\u1ecb tr\u00ed m\u1ed9t m\u1eabu, ki\u1ec3m \u0111\u1ecbnh v\u1ecb tr\u00ed hai m\u1eabu, ki\u1ec3m \u0111\u1ecbnh trung b\u00ecnh cho m\u1eabu c\u1eb7p v\u00e0 \u01b0\u1edbc l\u01b0\u1ee3ng h\u1ee3p l\u00ed c\u1ef1c \u0111\u1ea1i. Ki\u1ec3m \u0111\u1ecbnh Z c\u00f3 li\u00ean quan ch\u1eb7t ch\u1ebd v\u1edbi ki\u1ec3m \u0111\u1ecbnh T, nh\u01b0ng c\u00e1c ki\u1ec3m \u0111\u1ecbnh T \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n t\u1ed1t nh\u1ea5t trong ki\u1ec3m \u0111\u1ecbnh c\u00f3 c\u1ee1 m\u1eabu nh\u1ecf. <\/p>\n

Ngo\u00e0i ra, ki\u1ec3m \u0111\u1ecbnh T gi\u1ea3 \u0111\u1ecbnh \u0111\u1ed9 l\u1ec7ch chu\u1ea9n l\u00e0 kh\u00f4ng x\u00e1c \u0111\u1ecbnh, trong khi ki\u1ec3m \u0111\u1ecbnh Z gi\u1ea3 \u0111\u1ecbnh bi\u1ebft tr\u01b0\u01a1c \u0111\u1ed9 l\u1ec7ch chu\u1ea9n. N\u1ebfu \u0111\u1ed9 l\u1ec7ch chu\u1ea9n c\u1ee7a t\u1ed5ng th\u1ec3 l\u00e0 kh\u00f4ng x\u00e1c \u0111\u1ecbnh, th\u00ec ki\u1ec3m \u0111\u1ecbnh Z c\u00f3 gi\u1ea3 \u0111\u1ecbnh l\u00e0 ph\u01b0\u01a1ng sai m\u1eabu b\u1eb1ng v\u1edbi ph\u01b0\u01a1ng sai t\u1ed5ng th\u1ec3.<\/p>\n

Ki\u1ec3m \u0111\u1ecbnh gi\u1ea3 thuy\u1ebft<\/font><\/h3>\n

Ki\u1ec3m \u0111\u1ecbnh Z<\/b> c\u0169ng l\u00e0 m\u1ed9t ki\u1ec3m \u0111\u1ecbnh ki\u1ec3m tra gi\u1ea3 thuy\u1ebft trong \u0111\u00f3 tu\u00e2n theo ph\u00e2n ph\u1ed1i chu\u1ea9n. Ph\u00e9p th\u1eed z \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng t\u1ed1t nh\u1ea5t cho c\u00e1c m\u1eabu l\u1edbn h\u01a1n 30 v\u00ec theo \u0111\u1ecbnh l\u00ed gi\u1edbi h\u1ea1n trung t\u00e2m, s\u1ed1 l\u01b0\u1ee3ng m\u1eabu c\u00e0ng l\u1edbn th\u00ec ph\u00e2n ph\u1ed1i c\u1ee7a n\u00f3 c\u00e0ng g\u1ea7n ph\u00e2n ph\u1ed1i chu\u1ea9n. <\/p>\n

Khi ti\u1ebfn h\u00e0nh ki\u1ec3m \u0111\u1ecbnh Z, c\u1ea7n n\u00eau r\u00f5 gi\u1ea3 thuy\u1ebft kh\u00f4ng (gi\u1ea3 thuy\u1ebft ban \u0111\u1ea7u), gi\u1ea3 thuy\u1ebft ngh\u1ecbch, \u03b1 v\u00e0 z-score.<\/p>\n

V\u00ed d\u1ee5 v\u1ec1 Ki\u1ec3m \u0111\u1ecbnh Z m\u1ed9t m\u1eabu<\/font><\/h3>\n

Gi\u1ea3 s\u1eed m\u1ed9t nh\u00e0 \u0111\u1ea7u t\u01b0 mu\u1ed1n ki\u1ec3m tra xem l\u1ee3i nhu\u1eadn trung b\u00ecnh h\u00e0ng ng\u00e0y c\u1ee7a m\u1ed9t c\u1ed5 phi\u1ebfu c\u00f3 l\u1edbn h\u01a1n 1% hay kh\u00f4ng. M\u1ed9t m\u1eabu ng\u1eabu nhi\u00ean \u0111\u01a1n gi\u1ea3n g\u1ed3m 50 t\u1ec9 su\u1ea5t l\u1ee3i nhu\u1eadn \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng v\u00e0 c\u00f3 trung b\u00ecnh l\u00e0 2%. Gi\u1ea3 s\u1eed \u0111\u1ed9 l\u1ec7ch chu\u1ea9n c\u1ee7a l\u1ee3i nhu\u1eadn l\u00e0 2,5%. V\u00ec v\u1eady, gi\u1ea3 thuy\u1ebft kh\u00f4ng<\/b> l\u00e0 gi\u00e1 tr\u1ecb trung b\u00ecnh b\u1eb1ng 3% hay H0<\/sub> = 3%.<\/p>\n

Ng\u01b0\u1ee3c l\u1ea1i, gi\u1ea3 thuy\u1ebft ngh\u1ecbch<\/b> l\u00e0 li\u1ec7u l\u1ee3i nhu\u1eadn trung b\u00ecnh c\u00f3 l\u1edbn h\u01a1n 3% hay kh\u00f4ng hay H1 <\/sub>>3%. Gi\u1ea3 s\u1eed s\u1eed d\u1ee5ng ki\u1ec3m \u0111\u1ecbnh hai \u0111u\u00f4i v\u1edbi \u03b1 b\u1eb1ng 0.05%. Do \u0111\u00f3, ta c\u00f3 0,025% m\u1eabu trong m\u1ed7i \u0111u\u00f4i v\u00e0 \u03b1 c\u00f3 gi\u00e1 tr\u1ecb t\u1edbi h\u1ea1n l\u00e0 1,96 ho\u1eb7c -1,96. N\u1ebfu gi\u00e1 tr\u1ecb c\u1ee7a z l\u1edbn h\u01a1n 1,96 ho\u1eb7c nh\u1ecf h\u01a1n -1,96, ta b\u00e1c b\u1ecf gi\u1ea3 thuy\u1ebft kh\u00f4ng.<\/p>\n

Gi\u00e1 tr\u1ecb c\u1ee7a z \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng c\u00e1ch tr\u1eeb m\u1ee9c trung b\u00ecnh quan s\u00e1t \u0111\u01b0\u1ee3c c\u1ee7a c\u00e1c m\u1eabu cho gi\u00e1 tr\u1ecb l\u1ee3i t\u1ee9c trung b\u00ecnh \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho ki\u1ec3m \u0111\u1ecbnh, b\u1eb1ng 1% trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y. Ti\u1ebfp theo, chia gi\u00e1 tr\u1ecb tr\u00ean cho k\u1ebft qu\u1ea3 c\u1ee7a \u0111\u1ed9 l\u1ec7ch chu\u1ea9n chia cho c\u0103n b\u1eadc hai s\u1ed1 l\u01b0\u1ee3ng gi\u00e1 tr\u1ecb quan s\u00e1t.<\/p>\n

Do \u0111\u00f3, ki\u1ec3m \u0111\u1ecbnh th\u1ed1ng k\u00ea cho k\u1ebft qu\u1ea3 l\u00e0 2,83. Nh\u00e0 \u0111\u1ea7u t\u01b0 b\u00e1c b\u1ecf gi\u1ea3 thuy\u1ebft kh\u00f4ng v\u00ec z l\u1edbn h\u01a1n 1,96 v\u00e0 k\u1ebft lu\u1eadn r\u1eb1ng l\u1ee3i nhu\u1eadn trung b\u00ecnh h\u00e0ng ng\u00e0y l\u1edbn h\u01a1n 1%.<\/p>\n

C\u00e1c \u00fd ch\u00ednh<\/font><\/h3>\n

– Ki\u1ec3m \u0111\u1ecbnh Z<\/b> l\u00e0 m\u1ed9t ki\u1ec3m \u0111\u1ecbnh th\u1ed1ng k\u00ea x\u00e1c \u0111\u1ecbnh xem hai gi\u00e1 tr\u1ecb trung b\u00ecnh t\u1ed5ng th\u1ec3 c\u00f3 kh\u00e1c nhau hay kh\u00f4ng khi ph\u01b0\u01a1ng sai \u0111\u01b0\u1ee3c bi\u1ebft v\u00e0 k\u00edch th\u01b0\u1edbc m\u1eabu l\u1edbn.<\/p>\n

– N\u00f3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 ki\u1ec3m tra c\u00e1c gi\u1ea3 thuy\u1ebft trong \u0111\u00f3 ki\u1ec3m \u0111\u1ecbnh Z c\u00f3 ph\u00e2n ph\u1ed1i chu\u1ea9n.<\/p>\n

– Gi\u00e1 tr\u1ecb th\u1ed1ng k\u00ea z, hay z-score, l\u00e0 m\u1ed9t gi\u00e1 tr\u1ecb bi\u1ec3u th\u1ecb k\u1ebft qu\u1ea3 t\u1eeb ph\u00e9p th\u1eed z.<\/p>\n

– C\u00e1c ki\u1ec3m \u0111\u1ecbnh Z c\u00f3 li\u00ean quan ch\u1eb7t ch\u1ebd v\u1edbi c\u00e1c ki\u1ec3m \u0111\u1ecbnh T, nh\u01b0ng c\u00e1c ki\u1ec3m \u0111\u1ecbnh T \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n t\u1ed1t nh\u1ea5t khi ki\u1ec3m \u0111\u1ecbnh c\u00f3 c\u1ee1 m\u1eabu nh\u1ecf.<\/p>\n

– Ngo\u00e0i ra, c\u00e1c ki\u1ec3m \u0111\u1ecbnh T gi\u1ea3 \u0111\u1ecbnh \u0111\u1ed9 l\u1ec7ch chu\u1ea9n l\u00e0 kh\u00f4ng x\u00e1c \u0111\u1ecbnh, trong khi c\u00e1c ki\u1ec3m \u0111\u1ecbnh Z g\u1ec9a \u0111\u1ecbnh bi\u1ebft tr\u01b0\u1edbc \u0111\u1ed9 l\u1ec7ch chu\u1ea9n.<\/p>\n

(Theo Investopedia<\/i>)<\/p>\n<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

\n Ki\u1ec3m \u0111\u1ecbnh Z (ti\u1ebfng Anh: Z-Test) l\u00e0 m\u1ed9t h\u00ecnh th\u1ee9c ki\u1ec3m \u0111\u1ecbnh th\u1ed1ng k\u00ea \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh xem hai gi\u00e1 tr\u1ecb trung b\u00ecnh t\u1ed5ng th\u1ec3 c\u00f3 kh\u00e1c nhau hay kh\u00f4ng khi bi\u1ebft c\u00e1c ph\u01b0\u01a1ng sai v\u00e0 k\u00edch th\u01b0\u1edbc m\u1eabu l\u1edbn.\n <\/div>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[414],"tags":[],"_links":{"self":[{"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/posts\/26100"}],"collection":[{"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/comments?post=26100"}],"version-history":[{"count":0,"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/posts\/26100\/revisions"}],"wp:attachment":[{"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/media?parent=26100"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/categories?post=26100"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/masterskills.org\/blog\/wp-json\/wp\/v2\/tags?post=26100"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}