Page 170 - สถิติทางวิทยาศาสตร์สุขภาพ เพื่อการวิจัย

π”¡“ª√—∫ Ÿµ√‡æ◊ËÕÀ“§à“ Z ‰¥â¥—ßπ’È
Ú

np( - p ) 2
Z = T C - Z
Ú p( - Ò
2 1 p)
‚¥¬∑’Ë p=(p + p )/2
T C
p = —¥ à«π„π°≈ÿà¡∑¥≈Õß
T
p = —¥ à«π„π°≈ÿࡧ«∫§ÿ¡
C
Ò= Ò error ·≈– Ú = Ú error
n= ¢π“¥µ—«Õ¬à“ßµàÕ°≈ÿà¡∑’Ë„™â„π°“√»÷°…“

µ—«Õ¬à“ß∑’Ë 9.5

„π°“√»÷°…“‡ª√’¬∫‡∑’¬∫°“√√—°…“ºŸâªÉ«¬ 2 «‘∏’ ‚¥¬„™âµ—«Õ¬à“ß°≈ÿà¡≈– 50 §π

º≈°“√»÷°…“æ∫«à“ p = 0.7, p = 0.5 ∑’Ë Ò = 0.05 º≈°“√∑¥ Õ∫·µ°µà“ß°—πÕ¬à“߉¡à¡’
T C
π—¬ ”§—≠ π”º≈°“√»÷°…“∑’ˉ¥â¡“§”π«≥Õ”π“®°“√∑¥ Õ∫‰¥â¥—ßπ’È
®–‰¥â«à“ n = 50, p = 0.7, p = 0.5, Ò = 0.05 Æ Z = 1.65
T C Ò
07. + 05.
§”π«≥§à“ p = = 0.6
2

50 0 7 - 05 . ) 2
(.
Z = - 1.65 = 0.40
Ú
0 6 1 -
2 ¥ .( 0 6 . )
Z = 0.40 Æ Ú = 0.34 Õ”π“®°“√∑¥ Õ∫ = 1 - Ú = 1 - 0.34 = 0.66
Ú
„π°“√‡ª√’¬∫‡∑’¬∫¥—ß°≈à“«¡’Õ”π“®°“√∑¥ Õ∫ = 0.66
®“°§à“Õ”π“®°“√∑¥ Õ∫√âÕ¬≈– 66 ‡¡◊ËÕ¥Ÿ®“°§à“ p ·≈– p ´÷Ëß·µ°µà“ß°—π
T C
§àÕπ¢â“ß¡“° ∂Ⓡæ‘Ë¡¢π“¥µ—«Õ¬à“ß„Àâ¡“°°«à“π’È°Áπà“®–æ∫§«“¡·µ°µà“߉¥â

°“√§”π«≥Õ”π“®°“√∑¥ Õ∫°√≥’°“√‡ª√’¬∫‡∑’¬∫·∫∫Õ◊Ëπ „À⧔π«≥®“° Ÿµ√

§”π«≥¢π“¥µ—«Õ¬à“ß ‚¥¬·∑π§à“¢π“¥µ—«Õ¬à“ß §«“¡·ª√ª√«π §«“¡º‘¥æ≈“¥ Ò ·≈–
§«“¡µà“ߢÕߺ≈∑’ˉ¥â®“°°“√»÷°…“ §”π«≥À“§à“ Z ®“°§à“ Z ‡ªî¥µ“√“߇æ◊ËÕÀ“§à“ Ú
Ú Ú
·≈–§”π«≥§à“Õ”π“®°“√∑¥ Õ∫ (1 - Ú) ‰¥â

9.6 Õ”π“®°“√∑¥ Õ∫ 169

∫∑∑’Ë 9 169 29/7/09, 5:36 PM