Data rarely comes in usable form. Data wrangling and exploratory data analysis are the difference between a good data science model and garbage in, garbage out.

Multivariate Exploratory Analysis of Ordinal Data in Ecology: Pitfalls, Problems and Solutions, Journal of Vegetation Science, Vol. 16, No. 5 (Oct., 2005), pp. 497-510 ...

Exploratory data analysis is an attitude, a flexibility, and a reliance on display, NOT a bundle of techniques, and should be so taught. Confirmatory data analysis, by contrast, is easier to teach and ...