# Confidence intervals and different methods of sampling

I have two samples collected from the same population, where each sample is collected using a different method of selection, and both samples are large enough for the distribution of the sample distribution of the mean to be normal.

Now, when calculating two 95% confidence intervals for the mean, using each of the two samples, I get two non-overlapping intervals, so I can be fairly confident that one of the two samples suggest a larger population mean than the other sample suggest, or in other words, they are suggesting two different population means even-though they are sampled from the same population.

So, my question is now, is it valid to conclude that one, or both, of the sampling methods are flawed due to the discrepancy in the population means predicted by the two methods?