Levene's Test for Equality of Variances t-test for Equality of Means
  F Sig. t df Sig. (2-tailed)
Pb ug/gm Equal variances assumed 8.876 .004 4.911 98 .000
Equal variances not assumed     8.395 79.332 .000
Table 4: Result of Independent Sample T-Test for Lead Concentration