\u00dd ngh\u0129a th\u1ed1ng k\u00ea l\u00e0 m\u1ed9t trong nh\u1eefng thu\u1eadt ng\u1eef ch\u00fang ta th\u01b0\u1eddng nghe m\u00e0 kh\u00f4ng th\u1ef1c s\u1ef1 hi\u1ec3u r\u00f5. Khi ai \u0111\u00f3 tuy\u00ean b\u1ed1 d\u1eef li\u1ec7u ch\u1ee9ng minh quan \u0111i\u1ec3m c\u1ee7a h\u1ecd, ch\u00fang ta g\u1eadt \u0111\u1ea7u v\u00e0 ch\u1ea5p nh\u1eadn, v\u00ec ch\u00fang ta m\u1eb7c \u0111\u1ecbnh r\u1eb1ng c\u00e1c nh\u00e0 th\u1ed1ng k\u00ea \u0111\u00e3 th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p to\u00e1n ph\u1ee9c t\u1ea1p mang l\u1ea1i k\u1ebft qu\u1ea3 kh\u00f4ng th\u1ec3 nghi ng\u1edd. Tr\u00ean th\u1ef1c t\u1ebf, \u00fd ngh\u0129a th\u1ed1ng k\u00ea kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t kh\u00e1i ni\u1ec7m ph\u1ee9c t\u1ea1p \u0111\u00f2i h\u1ecfi nhi\u1ec1u n\u0103m nghi\u00ean c\u1ee9u \u0111\u1ec3 n\u1eafm v\u1eefng, m\u00e0 l\u00e0 m\u1ed9t \u00fd t\u01b0\u1edfng \u0111\u01a1n gi\u1ea3n m\u00e0 m\u1ecdi ng\u01b0\u1eddi c\u00f3 th\u1ec3 – v\u00e0 n\u00ean – hi\u1ec3u. Gi\u1ed1ng nh\u01b0 h\u1ea7u h\u1ebft c\u00e1c kh\u00e1i ni\u1ec7m th\u1ed1ng k\u00ea kh\u00e1c, \u00fd ngh\u0129a th\u1ed1ng k\u00ea \u0111\u01b0\u1ee3c x\u00e2y d\u1ef1ng d\u1ef1a tr\u00ean m\u1ed9t v\u00e0i \u00fd t\u01b0\u1edfng \u0111\u01a1n gi\u1ea3n: ki\u1ec3m \u0111\u1ecbnh gi\u1ea3 thuy\u1ebft, ph\u00e2n ph\u1ed1i chu\u1ea9n v\u00e0 gi\u00e1 tr\u1ecb p (p-value). Trong b\u00e0i vi\u1ebft n\u00e0y, t\u00f4i s\u1ebd tr\u00ecnh b\u00e0y ng\u1eafn g\u1ecdn v\u1ec1 t\u1ea5t c\u1ea3 c\u00e1c kh\u00e1i ni\u1ec7m n\u00e0y.<\/p>\n\n\n\n
\u00dd t\u01b0\u1edfng \u0111\u1ea7u ti\u00ean ch\u00fang ta ph\u1ea3i th\u1ea3o lu\u1eadn l\u00e0 ki\u1ec3m \u0111\u1ecbnh gi\u1ea3 thuy\u1ebft (hypothesis testing), m\u1ed9t k\u1ef9 thu\u1eadt \u0111\u1ec3 ki\u1ec3m tra m\u1ed9t l\u00fd thuy\u1ebft b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng d\u1eef li\u1ec7u. \u201cGi\u1ea3 thuy\u1ebft\u201d \u0111\u1ec1 c\u1eadp \u0111\u1ebfn ni\u1ec1m tin ban \u0111\u1ea7u c\u1ee7a nh\u00e0 nghi\u00ean c\u1ee9u v\u1ec1 t\u00ecnh hu\u1ed1ng tr\u01b0\u1edbc khi nghi\u00ean c\u1ee9u. L\u00fd thuy\u1ebft ban \u0111\u1ea7u n\u00e0y \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 gi\u1ea3 thuy\u1ebft thay th\u1ebf (alternative hypothesis) v\u00e0 \u0111i\u1ec1u ng\u01b0\u1ee3c l\u1ea1i \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 gi\u1ea3 thuy\u1ebft r\u1ed7ng hay gi\u1ea3 thuy\u1ebft v\u00f4 hi\u1ec7u (null hypothesis). V\u00ed d\u1ee5<\/p>\n\n\n\n
Gi\u1ea3 thuy\u1ebft thay th\u1ebf: chi\u1ebfn l\u01b0\u1ee3c \u0111\u1ea7u t\u01b0 c\u1ee7a t\u00f4i t\u1ea1o ra t\u1ef7 su\u1ea5t l\u1ee3i nhu\u1eadn trung b\u00ecnh cao h\u01a1n vi\u1ec7c mua v\u00e0 n\u1eafm gi\u1eef d\u00e0i h\u1ea1n m\u1ed9t c\u1ed5 phi\u1ebfu.<\/p>\n\n\n\n
Gi\u1ea3 thuy\u1ebft r\u1ed7ng: chi\u1ebfn l\u01b0\u1ee3c \u0111\u1ea7u t\u01b0 c\u1ee7a t\u00f4i kh\u00f4ng t\u1ea1o ra t\u1ef7 su\u1ea5t l\u1ee3i nhu\u1eadn trung b\u00ecnh cao h\u01a1n vi\u1ec7c mua v\u00e0 n\u1eafm gi\u1eef d\u00e0i h\u1ea1n m\u1ed9t c\u1ed5 phi\u1ebfu.<\/p>\n\n\n\n
Ki\u1ec3m \u0111\u1ecbnh gi\u1ea3 thuy\u1ebft l\u00e0 m\u1ed9t trong nh\u1eefng n\u1ec1n t\u1ea3ng c\u1ee7a th\u1ed1ng k\u00ea v\u00e0 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 \u0111\u00e1nh gi\u00e1 k\u1ebft qu\u1ea3 c\u1ee7a h\u1ea7u h\u1ebft c\u00e1c nghi\u00ean c\u1ee9u. Nh\u1eefng nghi\u00ean c\u1ee9u n\u00e0y c\u00f3 th\u1ec3 l\u00e0 b\u1ea5t c\u1ee9 \u0111i\u1ec1u g\u00ec t\u1eeb m\u1ed9t th\u1eed nghi\u1ec7m y t\u1ebf \u0111\u1ec3 \u0111\u00e1nh gi\u00e1 hi\u1ec7u qu\u1ea3 c\u1ee7a thu\u1ed1c \u0111\u1ebfn m\u1ed9t nghi\u00ean c\u1ee9u quan s\u00e1t \u0111\u00e1nh gi\u00e1 m\u1ed9t k\u1ebf ho\u1ea1ch t\u1eadp th\u1ec3 d\u1ee5c. \u0110i\u1ec3m chung c\u1ee7a t\u1ea5t c\u1ea3 c\u00e1c nghi\u00ean c\u1ee9u l\u00e0 ch\u00fang \u0111\u1ec1u quan t\u00e2m \u0111\u1ebfn vi\u1ec7c so s\u00e1nh gi\u1eefa hai nh\u00f3m ho\u1eb7c gi\u1eefa m\u1ed9t nh\u00f3m v\u1edbi to\u00e0n b\u1ed9 qu\u1ea7n th\u1ec3. Ch\u1eb3ng h\u1ea1n trong l\u0129nh v\u1ef1c y t\u1ebf, ch\u00fang ta c\u00f3 th\u1ec3 so s\u00e1nh th\u1eddi gian b\u00ecnh ph\u1ee5c trung b\u00ecnh gi\u1eefa c\u00e1c nh\u00f3m d\u00f9ng hai lo\u1ea1i thu\u1ed1c kh\u00e1c nhau.<\/p>\n\n\n\n
C\u00e1c ph\u00e9p ki\u1ec3m \u0111\u1ecbnh gi\u1ea3 thuy\u1ebft cho ph\u00e9p ch\u00fang ta x\u00e1c \u0111\u1ecbnh gi\u1ea3 thuy\u1ebft n\u00e0o, gi\u1ea3 thuy\u1ebft r\u1ed7ng hay gi\u1ea3 thuy\u1ebft thay th\u1ebf, \u0111\u01b0\u1ee3c h\u1ed7 tr\u1ee3 t\u1ed1t h\u01a1n b\u1edfi b\u1eb1ng ch\u1ee9ng d\u1eef li\u1ec7u. Gi\u1ea3 thuy\u1ebft ta c\u1ea7n ki\u1ec3m \u0111\u1ecbnh l\u00e0 gi\u1ea3 thuy\u1ebft r\u1ed7ng, n\u1ebfu nh\u01b0 ph\u00e9p ki\u1ec3m \u0111\u1ecbnh c\u00f3 th\u1ec3 b\u00e1c b\u1ecf gi\u00e1 thuy\u1ebft r\u1ed7ng, ta c\u00f3 th\u1ec3 k\u1ebft lu\u1eadn gi\u1ea3 thuy\u1ebft thay th\u1ebf c\u00f3 \u00fd ngh\u0129a th\u1ed1ng k\u00ea, v\u00e0 ng\u01b0\u1ee3c l\u1ea1i. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 ph\u00e9p ki\u1ec3m \u0111\u1ecbnh th\u00f4ng d\u1ee5ng:<\/p>\n\n\n\n
Ki\u1ec3m \u0111\u1ecbnh Z (Z-test)<\/em><\/strong><\/p>\n\n\n\n Ki\u1ec3m \u0111\u1ecbnh Z l\u00e0 b\u1ea5t k\u1ef3 ki\u1ec3m \u0111\u1ecbnh th\u1ed1ng k\u00ea n\u00e0o m\u00e0 ph\u00e2n ph\u1ed1i c\u1ee7a d\u1eef li\u1ec7u c\u1ea7n ki\u1ec3m \u0111\u1ecbnh theo gi\u1ea3 thuy\u1ebft r\u1ed7ng g\u1ea7n gi\u1ed1ng v\u1edbi ph\u00e2n ph\u1ed1i chu\u1ea9n. Ki\u1ec3m \u0111\u1ecbnh Z d\u1ef1a tr\u00ean ki\u1ec3m tra gi\u00e1 tr\u1ecb trung b\u00ecnh c\u1ee7a m\u1ed9t ph\u00e2n ph\u1ed1i m\u00e0 ta \u0111\u00e3 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c ph\u01b0\u01a1ng sai c\u1ee7a to\u00e0n b\u1ed9 qu\u1ea7n th\u1ec3. Do \u0111\u00f3, ki\u1ec3m \u0111\u1ecbnh Z s\u1ebd th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng n\u1ebfu k\u00edch c\u1ee1 m\u1eabu l\u1edbn ho\u1eb7c \u0111\u00e3 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c ph\u01b0\u01a1ng sai c\u1ee7a c\u1ea3 qu\u1ea7n th\u1ec3.<\/p>\n\n\n\n Ki\u1ec3m \u0111\u1ecbnh T (T-test)<\/em><\/strong><\/p>\n\n\n\n Ki\u1ec3m \u0111\u1ecbnh T th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng n\u1ebfu ph\u01b0\u01a1ng sai c\u1ee7a c\u1ea3 qu\u1ea7n th\u1ec3 kh\u00f4ng x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c v\u00e0 k\u00edch th\u01b0\u1edbc m\u1eabu kh\u00f4ng l\u1edbn (n <30).<\/p>\n\n\n\n ANOVA (Analysis of Variance)<\/em><\/strong><\/p>\n\n\n\n ANOVA l\u00e0 ki\u1ec3m \u0111\u1ecbnh \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh k\u1ebft qu\u1ea3 th\u1eed nghi\u1ec7m c\u00f3 \u00fd ngh\u0129a th\u1ed1ng k\u00ea hay kh\u00f4ng. ANOVA m\u1ed9t chi\u1ec1u (one way ANOVA) so s\u00e1nh hai gi\u00e1 tr\u1ecb trung b\u00ecnh t\u1eeb hai nh\u00f3m \u0111\u1ed9c l\u1eadp v\u1edbi ch\u1ec9 m\u1ed9t bi\u1ebfn \u0111\u1ed9c l\u1eadp. ANOVA hai chi\u1ec1u l\u00e0 ph\u1ea7n m\u1edf r\u1ed9ng c\u1ee7a ANOVA m\u1ed9t chi\u1ec1u s\u1eed d\u1ee5ng hai bi\u1ebfn \u0111\u1ed9c l\u1eadp.<\/p>\n\n\n\n Ki\u1ec3m \u0111\u1ecbnh Chi-Square (Chi-Square test)<\/em><\/strong><\/p>\n\n\n\n Ki\u1ec3m \u0111\u1ecbnh Chi-Square ki\u1ec3m tra xem m\u1ed9t m\u00f4 h\u00ecnh g\u1ed3m t\u1eadp h\u1ee3p c\u00e1c d\u1eef li\u1ec7u r\u1eddi r\u1ea1c (discrete data) c\u00f3 g\u1ea7n v\u1edbi ph\u00e2n ph\u1ed1i chu\u1ea9n hay kh\u00f4ng. Chi-Square Test for Independence l\u00e0 ki\u1ec3m \u0111\u1ecbnh d\u00f9ng \u0111\u1ec3 ki\u1ec3m tra xem hai bi\u1ebfn kh\u00e1c nhau c\u00f3 quan h\u1ec7 n\u00e0o kh\u00f4ng.<\/p>\n\n\n\n \u0110\u1ec3 ch\u1ea5p nh\u1eadn hay b\u00e1c b\u1ecf gi\u1ea3 thuy\u1ebft r\u1ed7ng, ta s\u1eed d\u1ee5ng gi\u00e1 tr\u1ecb p (p-value)<\/p>\n\n\n\n Gi\u00e1 tr\u1ecb p (p-value)<\/em><\/strong>: Khi p-value> \u03b1, ch\u00fang ta ch\u1ea5p nh\u1eadn gi\u1ea3 thuy\u1ebft r\u1ed7ng, c\u00f2n n\u1ebfu p-value \u2264 \u03b1, ch\u00fang ta b\u00e1c b\u1ecf gi\u1ea3 thuy\u1ebft r\u1ed7ng v\u00e0 ch\u00fang ta c\u00f3 th\u1ec3 k\u1ebft lu\u1eadn r\u1eb1ng ch\u00fang ta c\u00f3 m\u1ed9t k\u1ebft qu\u1ea3 c\u00f3 \u00fd ngh\u0129a th\u1ed1ng k\u00ea.<\/p>\n\n\n\n Gi\u00e1 tr\u1ecb t\u1edbi h\u1ea1n (critical value), hay \u03b1<\/em><\/strong>: l\u00e0 gi\u00e1 tr\u1ecb \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 so s\u00e1nh v\u1edbi gi\u00e1 tr\u1ecb p nh\u1eb1m ch\u1ea5p nh\u1eadn hay b\u00e1c b\u1ecf gi\u1ea3 thuy\u1ec7t. \u03b1 ph\u1ee5 thu\u1ed9c v\u00e0o \u0111\u1eb7c tr\u01b0ng c\u1ee7a lo\u1ea1i ph\u00e9p ki\u1ec3m \u0111\u1ecbnh v\u00e0 m\u1ee9c \u00fd \u0111\u1ed9 ch\u00ednh x\u00e1c c\u1ee7a ph\u00e9p ki\u1ec3m \u0111\u1ecbnh. Gi\u00e1 tr\u1ecb t\u1edbi h\u1ea1n th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0 \u03b1 = 0.05<\/p>\n","protected":false},"excerpt":{"rendered":" \u00dd ngh\u0129a th\u1ed1ng k\u00ea l\u00e0 m\u1ed9t trong nh\u1eefng thu\u1eadt ng\u1eef ch\u00fang ta th\u01b0\u1eddng nghe m\u00e0 kh\u00f4ng th\u1ef1c s\u1ef1 hi\u1ec3u r\u00f5. […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[3],"tags":[],"class_list":["post-114","post","type-post","status-publish","format-standard","hentry","category-kien-thuc"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=\/wp\/v2\/posts\/114","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=114"}],"version-history":[{"count":1,"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=\/wp\/v2\/posts\/114\/revisions"}],"predecessor-version":[{"id":115,"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=\/wp\/v2\/posts\/114\/revisions\/115"}],"wp:attachment":[{"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=114"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=114"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/datasciencebasic.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}