This report conducts statistical analyses of TSP and meteorological data at 25 locations in EPA Region 6. The primary goal of the study is to determine if the relationship between TSP and meteorology can be used to classify sites as to the types of sources causing nonattainment. It is found that decision-tree analysis is a very effective means of characterizing the relationship between TSP and meteorology, and that the TSP-meteorology relationship provides useful insights concerning the sources of high TSP levels. The results indicate distinct geographical patterns in causes of nonattainment within Region 6; specifically, wind-blown dust tends to be a major cause in and near the Texas Panhandle and a very minor cause in Arkansas and (probably) Louisiana. Despite a fair level of success with the method, however, we conclude that the TSP-meteorology relationship does not provide results that are definitive or quantitative enough for it to be used as the sole support for regulatory policy concerning causes of nonattainment. In addition to decision-tree analyses of the TSP-meteorology relationship, several other statistical studies are conducted herein. These include analyses of data quality, investigations of cumulative frequency distributions using log-normal and exponential distribution functions, computations of various statistical parameters for TSP data, regression studies of the TSP-meteorology relationship, nomogram analysis of the TSP-meteorology relationship, regression analysis of time series data, and meteorological normalization of time series data.