Exploratory data analysis should be interpreted carefully. When testing multiple models at once there is a high chance on finding at least one of them to be significant, but this can be due to a type 1 error . It is important to always adjust the significance level when testing multiple models with, for example, a Bonferroni correction . Also, one should not follow up an exploratory analysis with a confirmatory analysis in the same dataset. An exploratory analysis is used to find ideas for a theory, but not to test that theory as well. When a model is found exploratory in a dataset, then following up that analysis with a confirmatory analysis in the same dataset could simply mean that the results of the confirmatory analysis are due to the same type 1 error that resulted in the exploratory model in the first place. The confirmatory analysis therefore will not be more informative than the original exploratory analysis. 
There are a small number of schools (about 15% of all schools in our database) that have experienced only modest increases in GPAs over the last 15 to 20 years, but most of them have average GPAs that already exceed . There are no schools in our dataset that have been untouched by rising grades over the last 50 years. Grades went up significantly at all schools in our database in both the Vietnam era and the first half of the consumer era. That said, a few schools have had modest to negligible recent grade rises (and rarely, modest drops in grades) and have relatively low GPAs, as will be discussed in the next section.
There are many tools around to help turn data into graphics, but they can carry hefty price tags. The cost can make sense for professionals whose primary job is to find meaning in mountains of information, but you might not be able to justify such an expense if you or your users only need a graphics application from time to time, or if your budget for new tools is somewhat limited. If one of the higher-priced options is out of your reach, there are a surprising number of highly robust tools for data visualization and analysis that are available at no charge.