You have just completed your first real-world data analysis problem using SQL. In this chapter, you developed the skills necessary to develop hypotheses for problems and systematically gather the data required to support or reject them. You started this case study with a reasonably difficult problem of explaining an observed discrepancy in sales data and discovered two possible sources (launch timing and marketing campaign) for the difference while rejecting one alternative explanation (sales price).
While being a required skill for any data analyst, being able to understand and apply the scientific method in your exploration of problems will allow you to be more effective and find interesting threads of investigation. In this chapter, you used the SQL skills you have developed throughout this book, from simple
SELECT statements to aggregating complex data types, as well as windowing methods. After completing this chapter, you will be able to continue and repeat this type...