Page 50 - การวิจัยและสถิติทางการศึกษา หน่วยที่ 5
P. 50
5-40 °“√«‘®—¬·≈– ∂‘µ‘∑“ß°“√»÷°…“
µ“√“ß∑’Ë 5.6 °“√°”Àπ¥§≥ÿ ≈—°…≥–¢Õߪ√–™“°√¡’ 2 ·∫∫ §◊Õ ·∫∫ 50/50 ·≈– 80/20 ·∫∫
50/50 À¡“¬∂÷ß ª√–™“°√¡’§ÿ≥≈—°…≥–∑’˺⟫‘®—¬ π„®»÷°…“·µ°µà“ß°—π¡“° ·∫∫ 80/20 À¡“¬∂÷ߪ√–™“°√
à«π„À≠à¡’§ÿ≥≈—°…≥–∑’˧≈⓬§≈÷ß°—π‡ªìπ à«π„À≠à ¡’ à«ππâÕ¬‡∑à“π—Èπ∑’Ë·µ°µà“ß°—π „π°√≥’∑’ˉ¡à∑√“∫
§ÿ≥≈—°…≥–¢Õߪ√–™“°√§«√„™â·∫∫ 50/50 ”À√—∫§«“¡§≈“¥‡§≈◊ËÕπ„π°“√ ÿà¡°≈ÿࡵ—«Õ¬à“ß¡’ 3 √–¥—∫
§◊Õ ±3%, ±5%, ±10%
µ—«Õ¬à“߇™àπ „π°“√»÷°…“«‘®—¬§√—ÈßÀπ÷Ëߪ√–™“°√«‘®—¬¡’®”π«π 1,000 §π °”Àπ¥„Àâ¡’§«“¡§≈“¥
‡§≈◊ËÕπ¢Õß°“√ àÿ¡°≈àÿ¡µ—«Õ¬à“߉¡à‡°‘π ±5% ·≈–∑√“∫§ÿ≥≈—°…≥–¢Õߪ√–™“°√ à«π„À≠à¡’≈—°…≥–
§≈⓬§≈÷ß°—π ¢π“¥µ—«Õ¬à“ß∑’˵âÕß„™â‡¡◊ËÕæ‘®“√≥“®“°µ“√“ß∑’Ë 5.6 §◊ÕÕ¬à“ßπâÕ¬ 278 §π
4. °“√°”Àπ¥¢π“¥µ—«Õ¬à“ß‚¥¬„™âµ“√“ß ”‡√Á®√Ÿª¢Õ߇«≈™å·≈–‚§‡¡Õ√å (Welch and Comer)
‡«≈™å·≈–‚§‡¡Õ√å®—¥∑”µ“√“ß°”Àπ¥¢π“¥°≈ÿࡵ—«Õ¬à“ß‚¥¬¥—¥·ª≈ß¡“®“°µ“ߢÕß Hill, Roth ·≈– Arkin
(H.P Hill, J.L. Roth and H. Arkin 1983: 158) µ“√“ßπ’È°”Àπ¥¢π“¥°≈àÿ¡µ—«Õ¬à“ß‚¥¬æ‘®“√≥“
¢π“¥¢Õߪ√–™“°√ ·≈–¢π“¥§«“¡§≈“¥‡§≈◊ËÕπµ—Èß·µà ±1 ∂÷ß ±5 ‡ªÕ√凴Áπµå ∑’Ë√–¥—∫§«“¡‡™◊ËÕ¡—Ëπ 95
‡ªÕ√凴Áπµå ‚¥¬∂◊Õ«à“ª√–™“°√¡’§ÿ≥≈—°…≥–∑’Ë π„®»÷°…“√âÕ¬≈– 50
µ“√“ß∑’Ë 5.7 µ“√“ß°”Àπ¥¢π“¥°≈¡ÿà µ«— Õ¬“à ߢÕ߇«≈™å·≈–‚§‡¡Õ√å
¢π“¥ª√–™“°√ ¢π“¥¢Õß°≈¡ÿà µ«— Õ¬“à ß‚¥¬¡§’ «“¡§≈“¥‡§≈ËÕ◊ π¢Õß°“√ ÿ¡à °≈¡àÿ µ—«Õ¬“à ß
1,000................ ±1% ±2% ±3% ±4% ±5%
2,000................
3,000................ M∗ M∗ M∗ 375 278
4,000................ M∗ M∗ 696 462 322
5,000................ M∗ 1334 787 500 341
10,000.............. M∗ 1500 842 522 350
20,000.............. M∗ 1622 879 536 357
50,000.............. 4899 1936 964 566 370
100,000............ 6489 2144 1013 583 377
500,000 ¢÷Èπ‰ª 8057 2291 1045 593 381
8763 2345 1056 597 383
9423 2390 1065 600 384
∗ „π°√≥’π’È¢π“¥¢Õß°≈ÿࡵ—«Õ¬à“ßµâÕß¡“°°«à“√âÕ¬≈– 50 ¢Õߪ√–™“°√
∑Ë’¡“: Welch, Susan and Comer, John C. Quantitative Methods for Public Administration: Techniques and
Application. 1983, p. 158.
µ“√“ß∑’Ë 5.7 „π°“√ ”√«®¢âÕ¡Ÿ≈®“°°≈àÿ¡µ—«Õ¬à“ߧ√—ÈßÀπ÷Ëß∑’Ë¡’ª√–™“°√∑—ÈßÀ¡¥ 10,000 §π ∂â“
°”Àπ¥„Àâ¡’§«“¡§≈“¥‡§≈◊ËÕπ¢Õß°“√ ÿࡵ—«Õ¬à“߉¡à‡°‘π 4 ‡ªÕ√凴Áπµå ®–µâÕß ÿà¡°≈ÿࡵ—«Õ¬à“ß®”π«π
566 §π ·≈–∂⓵âÕß°“√„Àâ¡’§«“¡§≈“¥‡§≈◊ËÕπ‰¡à‡°‘π 3 ‡ªÕ√凴Áπµå ®–µâÕß„™â°≈àÿ¡µ—«Õ¬à“ß®”π«π 964 §π
