Dependent Variable Omnibus test

1 dependent variable

1.1 block 1: method = forward stepwise (conditional)
1.2 omnibus tests of model coefficients
1.3 block 2: method = forward stepwise (conditional)
1.4 omnibus tests of model coefficients
1.5 variables in equation

dependent variable

• grade — coded 1 if final grade a, 0 if final grade b or c.

the particular interest in research whether psi had significant effect on grade. tuce , gpa included control variables.

statistical analysis using logistic regression of grade on gpa, tuce , psi conducted in spss using stepwise logistic regression.

in output, block line relates chi-square test on set of independent variables tested , included in model fitting. step line relates chi-square test on step level while variables included in model step step. note in output step chi-square, same block chi-square since both testing same hypothesis tested variables enter on step non-zero. if doing stepwise regression, however, results different. using forward stepwise selection, researchers divided variables 2 blocks (see method on syntax following below).

logistic regression var=grade

/method=fstep psi / fstep gpa tuce

/criteria pin(.50) pout(.10) iterate(20) cut(.5).

the default pin value .05, changed researchers .5 insignificant tuce make in. in first block, psi alone gets entered, block , step chi test relates hypothesis h0: βpsi = 0. results of omnibus chi-square tests implies psi significant predicting grade more final grade of a.

block 1: method = forward stepwise (conditional)
omnibus tests of model coefficients

then, in next block, forward selection procedure causes gpa entered first, tuce (see method command on syntax before).

block 2: method = forward stepwise (conditional)
omnibus tests of model coefficients

the first step on block2 indicates gpa significant (p-value=0.003<0.05, α=0.05)

so, looking @ final entries on step2 in block2,

the step chi-square, .474, tells whether effect of variable entered in final step, tuce, differs zero. equivalent of incremental f test of parameter, i.e. tests h0: βtuce = 0.
the block chi-square, 9.562, tests whether either or both of variables included in block (gpa , tuce) have effects differ zero. equivalent of incremental f test, i.e. tests h0: βgpa = βtuce = 0.
the model chi-square, 15.404, tells whether of 3 independent variabls has significant effects. equivalent of global f test, i.e. tests h0: βgpa = βtuce = βpsi = 0.

tests of individual parameters shown on variables in equation table , wald test (w=(b/sb)2, b β estimation , sb standard error estimation ) testing whether individual parameter equals 0 . can, if want, incremental lr chi-square test. that, in fact, best way it, since wald test referred next biased under situations. when parameters tested separately, controlling other parameters, see effects of gpa , psi statistically significant, effect of tuce not. both have exp(β) greater 1, implying probability grade greater getting other grade depends upon teaching method psi , former grade average gpa.

variables in equation

a. variable(s) entered on step 1: psi