Page 245 - สถิติทางวิทยาศาสตร์สุขภาพ เพื่อการวิจัย

°≈ÿà¡„¥°≈ÿà¡Àπ÷Ë߇撬߰≈ÿࡇ¥’¬« „π∑“ߪؑ∫—µ‘„À⧔π«≥®“°¢âÕ¡Ÿ≈¢Õß°≈ÿà¡∑’Ë¡’º≈√«¡¢Õß≈”¥—∫∑’Ë∑’Ë¡’
§à“πâÕ¬
„Àâ T = º≈√«¡¢Õß≈”¥—∫∑’Ë∑’ˉ¥â®“°°“√®—¥≈”¥—∫∑’Ë√«¡¢Õß°≈ÿà¡∑’Ë¡’§à“πâÕ¬
1
n = ¢π“¥µ—«Õ¬à“ߢÕß°≈ÿà¡∑’Ë¡’§à“πâÕ¬
1
T= º≈µà“ߢÕߺ≈√«¡≈”¥—∫∑’Ë∑’ˉ¥â®“°°“√®—¥≈”¥—∫∑’Ë√«¡°—∫º≈√«¡≈”¥—∫∑’Ë
°≈ÿࡇ¥’¬«

®–‰¥â«à“T = T - n (n + 1)/2 [n (n + 1) ‡ªìπº≈√«¡¢Õß≈”¥—∫∑’Ë∑’˧‘¥‡©æ“–
1 1 1 1 1
°≈ÿࡇ¥’¬«]
∂â“§à“ T ¡’¢π“¥‡≈Á° º≈√«¡¢Õß≈”¥—∫∑’Ë∑’ˉ¥â®“°°“√®—¥≈”¥—∫∑’Ë√«¡À√◊Õ·¬°°≈ÿࡵà“ß°—π

‰¡à¡“° · ¥ß«à“µ—«Õ¬à“ß∑—Èß Õß¡“®“°ª√–™“°√∑’Ë¡’§à“¡—∏¬∞“π∑’˵à“ß°—π „π∑”πÕ߇¥’¬«°—π∂â“§à“ T
¡’¢π“¥„À≠àº≈√«¡¢Õß≈”¥—∫∑’˵à“ß°—π¡“° · ¥ß«à“µ—«Õ¬à“ß∑—Èß Õß¡“®“°ª√–™“°√∑’Ë¡’§à“¡—∏¬∞“π‰¡à

µà“ß°—π „π°“√µ—¥ ‘π„®„Àâπ”§à“§«“¡πà“®–‡ªìπ¢Õß§à“ T (§à“ P value) ‰ª‡∑’¬∫°—∫§à“√–¥—∫π—¬ ”§—≠
„π°“√¥”‡π‘π°“√∑¥ Õ∫º≈√«¡≈”¥—∫∑’Ë«‘≈§Õ°´—π¡’¢—ÈπµÕπ„π°“√¥”‡π‘π°“√¥—ßπ’È
1) π”¢âÕ¡Ÿ≈®“°∑—Èß 2 µ—«Õ¬à“ß¡“√«¡°—π‚¥¬‡√’¬ß≈”¥—∫®“°πâÕ¬‰ª¡“°
2) „Àâ≈”¥—∫∑’Ë¢âÕ¡Ÿ≈∑ÿ°§à“ „π°√≥’∑’Ë¢âÕ¡Ÿ≈¡’§à“‡∑à“°—π„Àâπ”≈”¥—∫∑’Ë¡“À“§à“‡©≈’ˬ ‡™àπ

¢âÕ¡Ÿ≈≈”¥—∫∑’Ë ≈”¥—∫∑’ˇ©≈’ˬ ¢âÕ¡Ÿ≈≈”¥—∫∑’Ë ≈”¥—∫∑’ˇ©≈’ˬ
7 + 8
78 7 7.5 = 7.5 69 10 11
2
10 11 12+ +
78 8 7.5 69 11 11 = 11
3
69 12 11

3) §”π«≥º≈√«¡¢Õß≈”¥—∫∑’Ë¢Õß·µà≈–°≈ÿà¡
4) „Àâ T ‡ªìπº≈√«¡¢Õß≈”¥—∫∑’Ë∑’ˉ¥â®“°°“√®—¥≈”¥—∫∑’Ë√«¡¢Õß°≈ÿà¡∑’Ë¡’§à“πâÕ¬
1
5) §”π«≥§à“ T = T - n (n + 1)/2
1 1 1
6) §”π«≥§à“ P value ¢Õß§à“ T

18.1.1 °“√§”π«≥§à“ P value ¢Õß°“√∑¥ Õ∫º≈√«¡≈”¥—∫∑’Ë
«‘≈§Õ°´—π°√≥’µ—«Õ¬à“ß¢π“¥‡≈Á°

„π°√≥’∑’˵—«Õ¬à“ß¡’¢π“¥‡≈Á° °“√§”π«≥§à“ P value ¢Õß ∂‘µ‘°“√∑¥ Õ∫º≈√«¡
≈”¥—∫∑’Ë«‘≈§Õ°´—π®–„™â«‘∏’°“√§”π«≥·∫∫«‘∏’·¡àπµ√ß (exact method)

244 ∫∑∑’Ë 18 ∂‘µ‘·∫∫‰¡à„™âæ“√“¡‘‡µÕ√å

∫∑∑’Ë18 244 3/8/09, 9:04 AM