Iowa Liquor Store Analysis

We were asked to look at Iowa liquor sales in General Assembly’s Data Science Immersive program. The goal of our analysis was to determine the best geographic location in Iowa in which to build a new liquor store. My analysis sought to determine location by maximizing the sales.

The data was a large dataset from the state of Iowa. It contained transaction level data for all stores holding a Class E liquor license in 2015 and part of 2016. The full dataset contained upwards of 2.7 million transactions. Missing values and 2,973 duplicated columns were removed from the raw data. Because of the large number of observations, I believe this had very little effect on my analysis. There were 99 counties, 383 cities, and 676 zip codes represented. A large number of observations are found in Polk County, the city of Des Moines, and the zip code 50010 (Ames, Iowa). There were 72 different categories of alcohol, each of which was highly differentiated. There were 1400 unique stores in the data set. Lastly, the vast majority of sales were of quantities of less than 100 bottles and of transactions less than $1,000.

The correct recording of sales data was one major assumption. Data entry error, missing information, and other data problems could drastically affect my predictive model. The majority of the feature engineering aspect of this analysis was done with dummy variables. I created dummy variables for the counties. This allowed the effect on sales to differ based on county.

I used correlation matrices to perform feature selection for the model. High correlations between sales (the target variable) and various features suggested those features would be predictive in the model. This analysis resulted in the first model including location dummy variables, state bottle retail (which can be thought of as price per bottle), and the number of bottles sold as features.

My first model was a linear regression run through Python’s Statsmodels. Both the number of bottles sold and state bottle retail were found to be statistically significant in affecting sales. Some of the location parameters were also statistically significant. The county that had the largest increase in sales was Dallas County and it was highly statistically significant. Based on this model, opening a liquor store in Dallas County would on average increase sales by about $56.25 above that of Polk County. Dallas County is located directly west of Des Moines. The analysis suggests opening a liquor store in Dallas County, Iowa would result in the highest sales.

There existed a risk of overfitting the model with the linear model including all of the counties in Iowa as dummy variables. Lasso Regression, or L1 regularization was used to reduce the error in the model and for feature selection. This ultimately did not change the conclusion that Dallas County was the best county in which to open a liquor store.

I built a second model to determine which features most strongly affected sales in Dallas County specifically. This secondary model looked to determine how state bottle retail, the number of bottles sold, and the volume of liquor sold (in liters) affected the sales of a Dallas County liquor store. Using Lasso Regression, the variable that had the most effect on sales was the number of bottles (followed by volume sold). Maximizing the number of bottles sold was the most effective way to increase sales, in Dallas County, Iowa. The number of bottles sold was a better predictor of high sales than item type, the average volume of a bottle, or anything else. This was a bit of a ‘duh’ moment for me. If we increase the number of bottles sold in a liquor store, sales will go up.

In conclusion, the model run on Iowa’s liquor sales data concluded that Dallas County, Iowa was the best locality in the state of Iowa in which to open a new liquor store and the best way to maximize sales in that county was to increase the number of bottles sold. Further analysis of the top performing stores in Dallas and the data associated with those stores would be necessary in order to develop a more robust business strategy. As always, this project’s Jupyter Notebook can be found on my GitHub.