Tuesday 1:45 PM–2:25 PM in Central Park West 6501 (6th fl)

Analyst’s Nightmare or Laundering Massive Spreadsheets

Feyzi Bagirov

Audience level:


Poor data quality frequently invalidates data analysis when performed on Excel data that underwent transformations, imputations, and manual manipulations. In this talk we will use Pandas to walk through Excel data analysis and illustrate several common pitfalls that make this analysis invalid.


The spreadsheet lives on, especially in sectors slow to adopt new technology, such as medicine and finance. Not only data is frequently stored and passed around in the spreadsheet formats, analysis is also frequently performed without leaving Excel. And when the data happens to be not as clean as you hoped it to be, serious errors occur and reproduce through the spreadsheet workcycle. Data quality issues such as duplicates and nulls, common practices such as copy-pastes, VLOOKUPS, and manual imputations as well as failure to properly understand and clean the data prior to making conclusions frequently lead to significant errors. Pandas library provides a powerful tool of ingesting, cleaning, transforming, and visualizing spreadsheet data that are either lacking in Excel or are very painful to implement given the number of worksheets required for a task. This talk will demonstrate several frequently occurring data issues and show how they can be dealt with in Pandas. We will start with an example of an analysis performed in an Excel spreadsheet and will perform step by step invalidation of its conclusions. For this talk we will use a synthetic dataset that artificially combines multiple data issues encountered in real life and provides a good illustration of common data pitfalls.

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