6 anak dalam relation2 cid monthlysalary 1 5000 2 6000 komputasi pendapatan

6 anak dalam relation2 cid monthlysalary 1 5000 2

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6 anak dalam relation2 cid monthly_salary 1 5000 2 6000 komputasi pendapatan tahunan dari pendapatan bulanan dalam relation1 tidak cocok dengan atribut annual_salary dalam relation 2
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Data Mining Data Preprocessing 2 Penanganan Redundansi dalam Integrasi Data 7 Data redundan sering terjadi saat integrasi beberapa database . Identifikasi objek : Atribut atau objek yang sama mungkin memiliki nama yang berbeda dalam database yang berbeda. Data yang diturunkan : Satu atribut mungkin merupakan atribut "turunan" di tabel lain, cth., pendapatan tahunan. Beberapa atribut redundan dapat dideteksi dengan analisis korelasi (correlation correlation) dan analisis kovarian (covariance analysis) . Integrasi data yang cermat dari berbagai sumber dapat membantu mengurangi / menghindari redudansi dan inkonsistensi dan meningkatkan kecepatan dan kualitas penambangan. Suatu atribut dikatakan redundan jika atribut tersebut dapat diperoleh dari atribut lainnya.
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Data Mining Data Preprocessing 2 Correlation Analysis (Nominal Data) 8 Χ 2 (chi-square) test Semakin besar nilai Χ 2 , semakin besar pula kemungkinan kedua variabel berkorelasi . The cells that contribute the most to the Χ 2 value are those whose actual count is very different from the expected count Correlation does not imply causality # of hospitals and # of car-theft in a city are correlated Both are causally linked to the third variable: population
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Data Mining Data Preprocessing 2 Correlation Analysis (Nominal Data) 9 Χ 2 (chi-square) test observed frequency (i.e., actual count) of the joint event expected frequency of number of data tuples number of tuples having value for number of tuples having value for column row
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Data Mining Data Preprocessing 2 An Example of Chi-Square Calculation 10 Play chess Not play chess Sum (row) Like science fiction 250(90) 200(360) 450 Not like science fiction 50(210) 1000(840) 1050 Sum(col.) 300 1200 1500 ???????
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