











English
or languish  Probing the ramifications
of Hong Kong's language policy 



Regression
Analysis
project index
 statistical modelling (prognostics)
 factor analysis (decision tree) 





Quality Assurance
 Goodness of fit
 Linearity  Examination of error terms with respect to each
independent variable
 Plot error terms against each independent variable.
 Partitioning the error terms
 Requires multiple observations of the dependent variable
for each value of the independent variables
 F  statistic
Comparing explained with unexplained error.
 Constant variance of the error term  Plot error terms against
predicted values of the dependent variable.
 Independence of error terms  Plot error terms against time.
 Normality of error term distribution.
 Construct a histogram of error terms
 Plot the cumulative standardized residuals against a straight
line.
 Addition of other variables  Regress error terms against
additional variable.
 Statistical significance
 T  tests against the null hypothesis for individual independent
variables.
 F  test (Coefficient of determination)  the ratio of explained
variation and unexplained variation
 Predictive value
 Only predict within the range of the sample estimated
 Strength of association  regression coefficients
 Beta coefficients  Coefficients resulting from standardized
data that permit direct comparison of the relative importance
of each independent variable on the dependent variable. Beta
values provide useful comparisons only when
 multicollinearity is small
 the number and kind of variables remain the same
 the range of values of each variable do not change.
 Selecting the best predictive model  Stepwise regression
analysis
 Backward elimination  a process of elimination whereby a
small number of independent variables are chosen from among many
independent variables with varying degrees of predictive power.
 Stepwise forward estimation  a process by which additional
independent variables are added to the regression equation based
on their ability to account for the unexplained error left by
other independent variables
 Dummy variables



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