Turhan et al.\cite{08Turhan} explored the effect of the Burak Filter on software defect prediction in their 2009 paper "On the relative value of cross-company and within-company data for defect prediction". Their results differ from the results that are presented in \chap{results}. In this section, I will discuss their results for Within Company, Cross Company and Nearest Neighbor augmented Cross Company over the 7 NASA datasets listed in \tion{datasets}.

\input{tables/burak-reproduction}
Although I were unable to reproduce the Cross Company results showing in Turhan's paper\cite{08Turhan}, I were able to duplicate the pattern of their results for Within Company and Nearest Neighbor in the majority of cases. Turhan et al. report that the Cross Company PD's reported in their paper were the highest reported as of the publication of their paper, and to our knowledge those results have not been duplicated. \tbl{burak-reproduction} shows Burak's original results and our reproduction of those. The ranks shown are the numerical orderings of the median PD and PF values. In our reproduction, PD and PF's for CM1, KC1, and KC2 followed the pattern displayed by Turhan. For KC3, MC2, and MW1, the PF matched the pattern. For PC1, the PD matched the pattern. The differences between our reproduction and Turhan's results may be caused by many factors, such as:

\bi
\item The datasets used for our results have been modified to use both the NASA datasets and the SoftLab datasets in the Cross-Company experiments.
\item Differences in algorithm implementations.
\item Minor differences in statistics gathering.
\ei

These results shown here are in contradiction to what will be shown in \tion{burak-results} and \tion{main-results}. The reason for this is in the statistics gathering. Turhan reported their results on both the defective and non-defective modules. I feel that only the records that involve the defective modules should be used for reporting on software defect prediction. This belief is because the defective modules are the modules I are attempting to identify. I also care about incorrectly classified non-defective modules, as they increase the cost of testing.

In the remainder of this thesis, I will report results as described in \tion{evaluation}.
