Page 124 - สถิติทางวิทยาศาสตร์สุขภาพ เพื่อการวิจัย

2
Û
®“°¢âÕ¡Ÿ≈„πµ“√“ß §”π«≥§à“ ‰¥â¥—ßπ’È
nad( - bc) 2
2
Û =
a ( + b a)( + c b)( + d c)( + d)
100 10( ¥ 48 - 2 ¥ 40) 2
= = 6.06
50 12 50 88¥ ¥ ¥

c 2 = 6.06 ‰¥â§à“ P value = 0.0138
()1
§à“ P value = 0.0138 πâÕ¬°«à“§à“√–¥—∫π—¬ ”§—≠ 0.05 ®÷ߪؑ‡ ∏ H · ¥ß«à“
0
≈—°…≥–ß“π¡’§«“¡ —¡æ—π∏å°—∫°“√‡ªìπ‚√§æ‘…µ–°—Ë«

2
º≈°“√«‘‡§√“–Àå¥â«¬ ∂‘µ‘ Û ¢Õßµ“√“ß 2 Ó 2 ®–„Àâ¢âÕ √ÿª‡™àπ‡¥’¬«°—∫°“√

‡ª√’¬∫‡∑’¬∫§à“ —¥ à«π√–À«à“ߪ√–™“°√ 2 °≈ÿࡥ⫬ ∂‘µ‘ Z „π°√≥’°“√∑¥ Õ∫ Õߥâ“π∑’ˉ¥â
2
Û
Õ∏‘∫“¬‰«â„πÀ—«¢âÕ 6.4 ‚¥¬∑’Ë§à“ P value ¢Õß∑—Èß ·≈– Z ®–¡’§à“‡∑à“°—π µ—«Õ¬à“ß∑’Ë 7.2
∂â“«‘‡§√“–Àå„π√Ÿª¢Õß°“√‡ª√’¬∫‡∑’¬∫ —¥ à«π ®–µ—Èߧ”∂“¡«à“ —¥ à«π¢Õß°“√ªÉ«¬¥â«¬‚√§
æ‘…µ–°—Ë«¢ÕߺŸâ∑”ß“π√â“π´àÕ¡À¡âÕπÈ”√∂¬πµå·µ°µà“ß®“°ºŸâ∑’Ë∑”ß“π„π ”π—°ß“πÀ√◊Õ‰¡à

®“°¢âÕ¡Ÿ≈„πµ—«Õ¬à“ß∑’Ë 7.2 §”π«≥§à“ ∂‘µ‘ Z ‰¥â¥—ßπ’È

10 2
p = = 0.20 p = = 0.04
1 2
50 50
np + n p (50 ¥ 0.20) + (50 ¥ 0.04)
2 2
11
p= = = 0.12
n + n 2 50 + 50
1
p - p
Z= 1 2
p 1 -( p) p 1 -( p)
+
n n
1 2
020 - 004
.
.
=
.
.
.
012 1 ( - 012) 012 1 ( - 012)
.
+
50 50
Z= 2.4618
§à“ Z = 2.46 ‰¥â§à“ P value = 0.0069
§à“ P value ®“° ∂‘µ‘ Z ∑’ˉ¥â‡ªìπ°√≥’∑¥ Õ∫À“§à“§«“¡πà“®–‡ªìπ¥â“π‡¥’¬«
(one sided P value) ∂â“®–‡ª≈’ˬπ‡ªìπ°“√∑¥ Õ∫À“§à“§«“¡πà“®–‡ªìπ 2 ¥â“π (two sided
P value) ®–µâÕߧŸ≥¥â«¬ 2 ´÷Ëß®–‰¥â 0.0069 Ó 2 = 0.0138 ´÷Ë߇∑à“°—∫§à“ P value ∑’ˉ¥â
2 2 2 2
Û
®“°§à“ ·≈–æ∫«à“§à“ Z = (2.4618) = 6.06 = Û

7.2 °“√∑¥ Õ∫§«“¡ —¡æ—π∏å√–À«à“ßµ—«·ª√∑’ˇªìπ¢âÕ¡Ÿ≈°≈ÿà¡ 123

∫∑∑’Ë 7 123 29/7/09, 4:05 PM