Abstract in English

References used

Allen L.Edwards “ Statistical Methods “ Second Edition , Holt , Rinchart & Winstuon , Inc , New York 1967
Norman D. ind Harry .S “ Applied Regression Analysis “ Second edition “ New York 1980
مصطفى زايد 1988 : الإحصاء ووصف البيانات، مطابع الشريف .

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