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psyc 60 computation practice 1 with answers

# psyc 60 computation practice 1 with answers - 67 SS y = s y...

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For the following data:... compute the mean, median, and major mode of dataset A, treating it as a sample compute the range, I.Q. range, M.A.D., variance, and standard deviation of dataset A as a sample compute the correlation between the data sets (treating columns as pairs) determine the least squares linear regression equation treating dataset A as the X variable predict the value of dataset B if dataset A is -4 and give a standard error of the estimate Dataset A: -8 -6 -6 -8 -6 -8 -5 -6 -4 Dataset B: -7 -8 -8 -5 -6 -6 -6 -4 -6 Averages: Sorted Data: -8 -8 -8 -6 -6 -6 -6 -5 -4 Major Mode: -6 Median: midpoint is datum number ( n +1) / 2 = 5, median is -6 Mean: ¯ x = x n = - 57 . 00 / 9 = -6.33 Variability: Variance and Standard Deviation: SS = summationdisplay ( x 2 ) - ( x ) 2 n = 377 - 3249 9 = 16 . 00 s 2 = SS n - 1 = 2.00 , s = 1.41 M.A.D. = | x - ¯ x | n = 1.11 Sorted Data: -8 -8 -8 -6 -6 -6 -6 -5 -4 Range: max - min = -4 - -8 = 4 Interquartile range: n +3 4 = 3 so count off 3 from each end , - 6 -- 8 = 2 Correlation and Prediction: Correlation: SP xy = summationdisplay ( xy ) - ( x )( y ) n = 354 . 00 - ( - 57 . 00)( - 56 . 00) 9 =
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Unformatted text preview: -. 67 SS y = s ( y 2 )-( ∑ y ) 2 n = 362-3136 9 = 13 . 56 SS x = s ( x 2 )-( ∑ x ) 2 n = 377-3249 9 = 16 . 00 r = SP xy r SS x SS y =-. 67 r (16 . 00)(13 . 56) =-0.05 Regression: b = SP xy SS x =-. 67 16 . 00 =-. 04 ¯ Y = ∑ y n =-56 . 00 / 9 =-6 . 22 , ¯ X = ∑ x n =-57 . 00 / 9 =-6 . 33 a = ¯ Y-( b )( ¯ X ) =-6 . 22-(-. 04)(-6 . 33) =-6 . 49 Y p = bX + a = Y p =(-0.04)(X)+(-6.49) Prediction: at x = -4, the prediction for y = (-. 04)(-4)+-6 . 49 =-6.32 Standard Error of Prediction: s y | x = R SS y (1-r 2 ) n-2 = R 13 . 56(1-(-. 05) 2 ) 9-2 = 1.39 Note: On the exam you should round all intermediate results to 2 decimal places. However the fnal answers on this key were computed using higher precision, thereFore there may be rounding discrepancies with solutions computed rounding at every step, especially For prediciton....
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