Page 171 - สถิติทางวิทยาศาสตร์สุขภาพ เพื่อการวิจัย

9.7 °“√„™â‚§âß°”≈—ߙ૬摮“√≥“¢π“¥µ—«Õ¬à“ß

ß“π«‘®—¬∑’Ëæ∫ªí≠À“«à“‰¡à “¡“√∂À“ºŸâªÉ«¬¡“∑”°“√»÷°…“‰¥â§√∫‡∑à“°—∫®”π«π∑’˧”π«≥

‰¥â®“° Ÿµ√ À√◊Õ∂â“®–À“„À≥â§√∫°Á®–µâÕß„™â‡«≈“‡°Á∫¢âÕ¡Ÿ≈π“π‡°‘π‰ª∑”„Àâº≈°“√»÷°…“∑’ˉ¥â‰¡à∑—π
µàÕ°“√‡ª≈’ˬπ·ª≈ß ®”‡ªìπ®–µâÕß≈¥¢π“¥µ—«Õ¬à“ß≈ß ´÷Ëß¡’º≈∑”„ÀâÕ”π“®°“√∑¥ Õ∫ (1 - Ú) ≈¥≈ß
Õ”π“®°“√∑¥ Õ∫πÕ°®“°®–·ª√µ“¡¢π“¥¢Õß n ·≈⫬—ß·ª√µ“¡§«“¡µà“ߢÕߺ≈

(p - p ) ¥â«¬ ¥—ßπ—Èπ®÷ß “¡“√∂π”°√“ø∑’Ë √â“ߢ÷Èπ®“°§«“¡ —¡æ—π∏å√–À«à“ß¢π“¥§«“¡µà“ߢÕß
T C
p - p °—∫Õ”π“®°“√∑¥ Õ∫´÷Ë߇√’¬°«à“‚§âß°”≈—ß (power curve) ¡“„™â™à«¬„π°“√µ—¥ ‘π„®‡æ◊ËÕ
T C
°”Àπ¥¢π“¥µ—«Õ¬à“߉¥â

«‘∏’ √â“ß‚§âß°”≈—ß∑”‰¥â¥—ßπ’È
1) °”Àπ¥¢π“¥µ—«Õ¬à“ß∑’Ë„À≠à∑’Ë ÿ¥∑’Ë “¡“√∂∑”‰¥â

2
n(p - p )
2) §”π«≥ Z ®“° Ÿµ√ Z = T C - Z ‚¥¬∑’Ë p = (p + p )/2
Ú Ú - Ò T C
( p
21 ) p
3) π”§à“ Z ¡“‡ªî¥µ“√“ßÀ“§à“ Ú ·≈–π”§à“∑’ˉ¥â¡“§”π«≥§à“Õ”π“®°“√∑¥ Õ∫ (1 - Ú)
Ú
4) √â“ß°√“ø· ¥ß§«“¡ —¡æ—π∏å√–À«à“ßÕ”π“®°“√∑¥ Õ∫°—∫§«“¡µà“ߢÕߺ≈ (p - p ) À√◊Õ
T C
§à“ p
T

µ—«Õ¬à“ß∑’Ë 9.6

°“√√—°…“‚√§µ‘¥‡™◊ÈÕ√–∫∫∑“߇¥‘πªí “«–¥â«¬«‘∏’√—°…“·∫∫‡¥‘¡ (conventional
treatment) ¡’Õ—µ√“°“√À“¬ 0.5 ·≈–º≈°“√√—°…“¥â«¬ gentamycin ®“°√“¬ß“π¡’Õ—µ√“
°“√À“¬ 0.7 ¢π“¥µ—«Õ¬à“ߺŸâªÉ«¬∑’Ë„™â„π°“√»÷°…“‡æ◊ËÕ®– √ÿª§«“¡·µ°µà“ߢÕߺ≈°“√√—°…“
¥—ß°≈à“«∑’Ë Ò = 0.05 ·≈– Ú = 0.2 ®–µâÕß„™â°≈ÿà¡≈– 130 §π ·µàºŸâªÉ«¬„π‚√ß欓∫“≈

¡’‡æ’¬ßªï≈– 50 §π ∂â“°”Àπ¥√–¬–‡«≈“°“√»÷°…“‰«â 2 ªï®– “¡“√∂À“µ—«Õ¬à“߉¥â‡æ’¬ß
°≈ÿà¡≈– 50 §π
„π°√≥’π’ȧ«√∑’Ë®– √â“ß‚§âß°”≈—ߙ૬„π°“√°”Àπ¥¢π“¥µ—«Õ¬à“ß «‘∏’°“√ √â“ß°√“ø

· ¥ßÕ”π“®°“√∑¥ Õ∫∑’Ë·ª√µ“¡§«“¡µà“ߢÕߺ≈ (p - p ) ∑”‰¥â¥—ßπ’È
T C
1) °”Àπ¥§à“ n = 50 ·≈– p = 0.5 ‰«â§ß∑’Ë
C
2) ‡ª≈’ˬπ§à“ p ‡ªìπ§à“µà“ßÊ ·≈⫧”π«≥À“Õ”π“®°“√∑¥ Õ∫∑ÿ°§à“¢Õß§à“ p
T T
∑’ˇª≈’Ë¬π‰ª º≈°“√§”π«≥· ¥ß„πµ“√“ß„πÀπâ“ 171
3) §à“Õ”π“®°“√∑¥ Õ∫∑’Ë§à“ p √–¥—∫µà“ßʇ¡◊ËÕ°”Àπ¥§à“ n = 50
T

170 ∫∑∑’Ë 9 °“√§”π«≥¢π“¥µ—«Õ¬à“ß·≈–Õ”π“®°“√∑¥ Õ∫

∫∑∑’Ë 9 170 9/7/09, 10:40 AM