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ß“π«‘®—¬ à«π„À≠àπ‘¬¡°”Àπ¥√–¥—∫π—¬ ”§—≠„Àâ¡’§à“‡∑à“°—∫ 0.05 À√◊Õ 0.01 ®“°
√–¥—∫π—¬ ”§—≠∑’Ë°”Àπ¥ ∂Ⓡªìπ°“√∑¥ Õ∫¥â“π‡¥’¬«®–π”§à“ a ‰ªÀ“§à“«‘°ƒµ∑’Ë„™â ”À√—∫
°“√µ—¥ ‘π„®

„π°√≥’∑’ˇªìπ°“√∑¥ Õ∫ Õߥâ“π®–π” a ∑’Ë°”Àπ¥À“√¥â«¬ Õß°àÕπ𔉪À“§à“
«‘°ƒµ¥â«¬«‘∏’°“√‡™àπ‡¥’¬«°—π ∑—Èßπ’È ‡æ√“– ¡¡µ‘∞“π∑“߇≈◊Õ°¢Õß°“√∑¥ Õ∫ Õߥâ“π
§«“¡º‘¥æ≈“¥®–∂Ÿ°·∫à߇ªìπ Õߥâ“π‡∑à“Ê°—π ¥â“π≈– a/2 ¥—ߪ√“°Ø„π¿“æ 4.9

1 - a 1 - a
‡¢µªØ‘‡ ∏ H 0 ‡¢µ¬Õ¡√—∫ H 0 ‡¢µªØ‘‡ ∏ H 0 ‡¢µ¬Õ¡√—∫ H 0

a a/2 a/2

®ÿ¥«‘°ƒµ t 0.05(29) = -1.7 ®ÿ¥«‘°ƒµ
°“√∑¥ Õ∫¥â“π‡¥’¬« °“√∑¥ Õ∫ Õߥâ“π

¿“æ 4.9 · ¥ß‡¢µªØ‘‡ ∏ H „π°√≥’°“√∑¥ Õ∫¥â“π‡¥’¬«·≈–°“√∑¥ Õ∫ Õߥâ“π
0

¢—Èπ∑’Ë 4 §”π«≥§à“ ∂‘µ‘∑’Ë„™â∑¥ Õ∫·≈–À“§à“ P value
®“° ∂‘µ‘∑’ˇ≈◊Õ°„π¢—ÈπµÕπ∑’Ë 2 π”¢âÕ¡Ÿ≈∑’ˇ°Á∫®“°µ—«Õ¬à“ß¡“§”π«≥§à“ ∂‘µ‘∑’Ë„™â
∑¥ Õ∫ §à“ ∂‘µ‘∑’˧”π«≥‰¥â®–„™â ”À√—∫°“√µ—¥ ‘π„® √ÿªº≈°“√∑¥ Õ∫ ¡¡µ‘∞“π„π¢—ÈπµÕπ

∑’Ë 5 ®“°µ—«Õ¬à“ß∑’Ë 4.2 §”π«≥§à“ ∂‘µ‘ t ‰¥â¥—ßπ’È

m = 1,000, x = 974, s = 94 ·≈– n = 30
x -m 974 - 1 000,
t = = = -1.5
s 94
n 30

°“√µ—¥ ‘π„® √ÿªº≈°“√∑¥ Õ∫ ¡¡µ‘∞“π∑’Ë∑”¡“·µà‡¥‘¡ §◊Õ°“√„™â§à“ ∂‘µ‘∑’Ë

§”π«≥‰¥â‡∑’¬∫°—∫§à“«‘°ƒµ ·µà∑’Ëπ‘¬¡„πªí®®ÿ∫—π‡ªìπ°“√µ—¥ ‘π„® √ÿªº≈°“√∑¥ Õ∫
¡¡µ‘∞“π‚¥¬„™â§à“ P value ‡∑’¬∫°—∫§à“√–¥—∫π—¬ ”§—≠ (a)

4.4 ¢—ÈπµÕπ„π°“√∑¥ Õ∫ ¡¡µ‘∞“π 77

∫∑∑’Ë 4 77 2/7/09, 3:46 PM