Pretest, posttest, and control group sample sets for the second
hypothesis were analogous to the first hypothesis test. Dependent
variables were the monthly average product quality score and the
monthly average quality issue rate. The independent variable was
the KM/QM strategy application time. A pretest was administered
to determine if a significant linear relationship existed between
time and product quality before the KM/QM strategy was
implemented at company B. After the KM/QM strategy was
implemented at company B, a posttest was performed over a six
year research period at company B as well as the control groups
of company A, C, and D. A regression analysis with a two-tail
t-test was applied for all sample sets to determine whether or not
there was a significant linear relationship between the variables.
The degree of freedom for the two-tail t-test was n-2, and the
level of significance was α= 0.05. Correlation between the KM/
QM strategy application time and product quality performance
characteristics was measured by getting the Pearson productmoment
correlation coefficient (PPMCC), denoted by r. Salkind
(2012) presented ranges for the sample correlation coefficient r
and its associated estimated relationship strength. The critical
values for the two-tailed t-test (tCV) were obtained from tables,
such as Levine et al. (2005). Microsoft Excel was used to perform
the regression analysis.