Page 41 - การวิจัยและสถิติทางการศึกษา หน่วยที่ 5
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°“√ÕÕ°·∫∫°“√‡≈◊Õ°°≈àÿ¡µ—«Õ¬à“ß 5-31
µ—«Õ¬à“ß∑’Ë 5.4 ºŸâ«‘®—¬µâÕß°“√»÷°…“§à“‡©≈’ˬ§«“¡§‘¥‡ÀÁπ¢Õßπ—°»÷°…“∑’Ë¡’µàÕ°“√®—¥°“√‡√’¬π
°“√ Õπ¢Õß “¢“«‘™“»÷°…“»“ µ√å¡À“«‘∑¬“≈—¬ ÿ‚¢∑—¬∏√√¡“∏‘√“™ ( ¡¡µ‘«à“·∫∫ Õ∫∂“¡‡ªìπ·∫∫¡“µ√
ª√–¡“≥§à“ 5 √–¥—∫) ®“°°“√»÷°…“∑’˺à“π¡“æ∫«à“§«“¡·ª√ª√«π¢Õߧ«“¡§‘¥‡ÀÁπ¡’§à“‡∑à“°—∫ 36
®ß§”π«≥À“¢π“¥µ—«Õ¬à“߇¡◊ËÕπ—°»÷°…“¢Õß “¢“«‘™“»÷°…“»“ µ√å¡’∑—ÈßÀ¡¥ 3,000 §π °”À𥧫“¡
§≈“¥‡§≈◊ËÕπ¡’§à“‰¡à‡°‘π 4 §–·ππ ∑’Ë√–¥—∫§«“¡‡™◊ËÕ¡—Ëπ 95%
®“°‚®∑¬å°”Àπ¥ N = 3,000 §π
σ2 = 36
e ≤4
∑’Ë√–¥—∫§«“¡‡™◊ËÕ¡—Ëπ 95% Z = 1.96
®“° Ÿµ√ n = NZ2σ2
Ne2 + Z2σ2
3,000(1.96)2(36)
n = 3,000(.4)2 + (1.96)2(36)
414892.8
=
480 + 138.2976 = 618.2976
= 671.02443
¥—ßπ—Èπ µâÕß„™â°≈àÿ¡µ—«Õ¬à“ßÕ¬à“ßπâÕ¬ 672 §π
µ—«Õ¬à“ß∑Ë’ 5.5 ®“°µ—«Õ¬à“ß∑’Ë 5.4 ∂â“°”Àπ¥√–¥—∫§«“¡‡™◊ËÕ¡—Ëπ 90% µâÕß„™â°≈àÿ¡µ—«Õ¬à“ß
π—°»÷°…“°’˧π
®“°‚®∑¬å°”Àπ¥ N = 3,000
σ2 = 36
e ≤ .4
∑’Ë√–¥—∫§«“¡‡™◊ËÕ¡—Ëπ 99% Z = 2.58
®“° Ÿµ√ n = NZ2σ2
Ne2 + Z2σ2
3,000(2.58)2(36)
n = 3,000(.4)2 + (2.58)2(36)
