Measurement of public perception via survey methods is an expensive endeavor. This is partially due to the cost of probability sampling in recruiting survey respondents. As a result, non-probability sampling has grown in popularity in survey research. While there appear to be some benefits to Internet-based survey methods such as easier administration of survey questionnaires, reduced social desirability bias and reduced survey satisficing, the relative accuracy of non-probability samples has recently been shown to be less reliable than probability samples (Yeager et al., 2009). However, if non-probability samples can be weighted or otherwise analyzed in ways that yield representative results, the merging of Internet data collection and non-probability samples may still be a viable approach to yielding accurate survey measurements. In this paper, we will present an analysis of non-probability and probability sampling survey data collected in the Netherlands. The Dutch Online Panel Comparison Study (NOPVO) involved 19 Internet survey companies collecting data from non-probability samples of the Dutch population using the same questionnaire, which asked questions on demographic and non-demographic topics. This paper covers a comparison between the accuracy of these companies and probability samples performed at the same time, using benchmarks from the Dutch Census to determine accuracy. The results of this analysis will further illuminate the relationship between accuracy and web-based survey methods, particularly with respect to the viability of weighting methods and non-probability sampling.