samlet årgang - Økonomisk Institut - Københavns Universitet

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NATIONALØKONOMISK TIDSSKRIFT 2005. NR. 3
Table 6. Results of the estimation, 2 nd year courses with math-variables.
Variable Course Course Course Course
212E 222 234 241
Intercept term 4.53*** 9.62*** 8.50*** 8.71***
DQ – – -5.39*** –
GPA*DQ – – 0.27** –
MOTAVR*DQ – – – –
DSCAND*DQ – – 2.77*** –
AGEADMIT – – – –
MGRADE 0.36* – – –
ALEVEL – – – –
Number of observations 32 21 31 –
R2 0.12* – 0.35*** –
OLD – – + +
Note: OLD: a plus means that a model with similar characteristics as the one in table 1 still applies to the
smaller data set. A minus means that this is not the case. * significant at the 10% level, ** significant at the
5% level, *** significant at the 1% level.
cant. In most cases we have been able to find new models and very often the math grade
enters the new equations significantly and with a positive sign. Also the explanatory
power is increased for all courses. Furthermore, it seems that the importance of the GPA
and the quota-variable has been reduced: only in two of the new models is the quotavariable
still significant. For the second year courses the inclusion of the math grade data
does not seem to add much – actually, very few observations are left for analysis here.
However, due to the reduced number of observations and the bias they introduce, we
should be a bit careful in our interpretations. We shall therefore tentatively conclude that
the math grade is an important factor to include in future models on these issues.
The last extension that we investigate here has to do with something that we
mentioned in the very beginning of our paper, viz. that the students’ performance may
improve considerably in a good learning environment. Thus, and in addition to our primary
goal of determining the importance of student background characteristics to
their performance, we test here whether the first year’s GPA has any explanatory value
for the second year performance. To investigate this hypothesis on our data, we ran
some additional regressions for the 2 nd year courses to see if adding the 1 st year GPA to