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µ—«Õ¬à“ß∑’Ë 18.1

π—°«‘®—¬µâÕß°“√»÷°…“«à“ºŸâªÉ«¬Õ—¡æ“µÀ≈—ß®“°‰¥â√—∫°“√ Õπ·≈–‡µ√’¬¡ºŸâªÉ«¬„Àâ

ª√—∫µ—«‡æ◊ËÕ°≈—∫‰ªÕ¬Ÿà∑’Ë∫â“𠧫“¡ “¡“√∂„π°“√ª√—∫µ—«¢ÕßÀ≠‘ߥ’°«à“™“¬À√◊Õ‰¡à ‚¥¬«—¥
§–·ππª√—∫µ—«‰¥â¥—ßπ’È ®ß √ÿªº≈°“√»÷°…“

°≈ÿà¡ 1 (™“¬) 50 70 60

°≈ÿà¡ 2 (À≠‘ß) 72 80 55 62

π”¢âÕ¡Ÿ≈¡“®—¥≈”¥—∫∑’Ë√«¡·≈–·¬°°≈ÿࡉ¥â¥—ßπ’È

‡√’¬ß≈”¥—∫ ≈”¥—∫∑’Ë°≈ÿà¡ 1 (™“¬) ≈”¥—∫∑’Ë°≈ÿà¡ 2 (À≠‘ß)
§–·ππ ≈”¥—∫∑’Ë §–·ππ ≈”¥—∫∑’Ë §–·ππ ≈”¥—∫∑’Ë

50 1 50 1 72 6
55 2 70 5 80 7
60 3 60 3 55 2
62 4 √«¡ (T ) 9 62 4
1
70 5 √«¡ 19
72 6

80 7

«‘∏’°“√§”π«≥§à“ P value ¥â«¬«‘∏’§«“¡πà“®–‡ªìπ·∫∫·¡àπµ√ß (exact probability)
∑”‚¥¬°“√π”¢âÕ¡Ÿ≈∑—Èß 2 °≈ÿà¡¡“√«¡°—π °≈ÿà¡™“¬ n = 3 °≈ÿà¡À≠‘ß n = 4 ¢âÕ¡Ÿ≈ 2 °≈ÿà¡
1 2
√«¡°—π®–¡’¢âÕ¡Ÿ≈ n = 7 ¥—ßπ—Èπ¢âÕ¡Ÿ≈·µà≈–µ—«®–¡’‚Õ°“ ‰¥â≈”¥—∫∑’˵—Èß·µà 1 ∂÷ß 7 ®“°

°“√∑’Ë°≈ÿà¡™“¬¡’º≈√«¡¢Õß≈”¥—∫∑’ËπâÕ¬°«à“ ®÷ßπ”®”π«π n = 3 ¡“§”π«≥º≈√«¡≈”¥—∫∑’Ë
∑’ˇªìπ‰ª‰¥â∑—ÈßÀ¡¥ ‡¡◊ËÕ n = 3 ·≈–≈”¥—∫∑’Ë∑’ˇªìπ‰ª‰¥âµ—Èß·µà 1 ∂÷ß 7 √“¬≈–‡Õ’¬¥· ¥ß
Õ¬Ÿà„πµ“√“ß 18.1

π”º≈√«¡¢Õß≈”¥—∫∑’Ë (T ) ¢Õß·µà≈–µ—«Õ¬à“ß¡“∑”µ“√“ß·®°·®ß§«“¡∂’Ë ·≈–
1
§”π«≥§à“§«“¡πà“®–‡ªìπ¢Õß°“√‰¥âº≈√«¡∑’褈ҵà“ßÊ √“¬≈–‡Õ’¬¥· ¥ß„πµ“√“ß 18.2 ‡™àπ
‚Õ°“ ∑’Ë®–¡’º≈√«¡ T ‡∑à“°—∫ 6 ¡’§à“§«“¡πà“®–‡ªìπ‡∑à“°—∫ 1/35 = 0.029 §”π«≥§à“
1
§«“¡πà“®–‡ªìπ – ¡ (Cum. Pr.) ·≈–§à“ T = T - n (n + 1)/2 ®–∑”„Àâ∑√“∫§à“
1 1 1
§«“¡πà“®–‡ªìπÀ√◊Õ§à“ P value ¢Õß∑ÿ°§à“¢Õß T
§à“ P value ¢Õß°“√∑¥ Õ∫º≈√«¡≈”¥—∫∑’Ë«‘≈§Õ°´—π¢Õß§à“ n n ·≈– T µà“ßÊ
1 2
‰¥â§”π«≥‰«â„πµ“√“ß 5

18.1 °“√∑¥ Õ∫º≈√«¡≈”¥—∫∑’Ë«‘≈§Õ°´—π 245

∫∑∑’Ë18 245 30/7/09, 3:01 PM