Data Analysis Journal

10/05/2022

A common question in product analytics is - which features in your product do users use the most? Check a simple SQL solution on how to calculate the most popular (or the most commonly used) user features across all users.

How to get the most popular features, products, or user activity in SQL

07/22/2021

A common challenge for data analysts is to deal with multiple currency conversions for revenue reporting. Here I describe how to convert different local currency values into one target currency for your analysis.

How to approach conversion rates for multiple currencies in SQL for revenue reporting

07/02/2021

The recent newsletter topic is an overview of a little sensitive, controversial, and a long-time pain of mine - Tableau.

A recap of data analysis publications, guides, and news over the past month.

06/25/2021

The last few weeks were brimming with many interesting events in the data world. Read a recap and a brief summary of what you may have missed -

A recap of the most important events in the data world over the last few weeks.

06/18/2021

Many analysts use mostly basic SQL and don't take full advantage of its functionality. Here I covered some advanced querying use cases and went over common complex functions

Building complex and advanced SQL queries for data analysis, data manipulation, and modeling

06/11/2021

A successful A/B test doesn't always increase company revenue or growth. +15% lift can have no impact. Learn about types of product experimentation and ways to evaluate its impact

How to measure A/B test success, and why product experiments can be tricky and not always effective.

06/01/2021

Technical interviews are stressful and time-consuming. Python questions can be very different for data engineering, data scientist, or data analyst interviews. In this article, I describe a set of common Python questions you are likely to encounter in your interview. https://dataanalysis.substack.com/p/python-questions-for-a-data-analyst

05/24/2021

Let’s say you are a data analyst supporting growth marketing initiatives and have to report which marketing campaign has made the biggest impact over the last few months. The most successful campaign should have the highest ROI and lead to the increased LTV. Your first step is to understand the Customer Acquisition Cost (known as CAC) to get there. In this article, I go thorough breakdown of CAC to highlight why it is important to measure correctly and the ways to improve it.

A close look at Customer Acquisition Cost, how to calculate it, and ways to improve CAC and user growth.

05/11/2021

Building a data-driven culture is not easy. Creating an environment where analysts can flourish and develop depends on many factors - leadership, budget, data strategy, data maturity, and so on. Investing into data culture magnifies analysis impact. We know it, we talk about it, but how do we make it happen?
Read my recent interview with Ziv Wangenheim, co-founder and CEO at Rupert (https://www.hirupert.com/) whose mission is to improve and automate data process and discovery so that analysts can focus on real data analysis.
https://dataanalysis.substack.com/p/expert-insight-ziv-wangenheim-how

An insightful look into some of the biggest challenges for data analysts, and how to overcome them while building a data-driven culture

05/06/2021

Have you ever received a take-home assignment to write a SQL query to solve a problem? Did you break your brain over how to install a database, replicate a table with a sample of data (that is usually not provided) and test your SQL? Here is the logic and steps on how to install and replicate a database with a sample of data on your computer.

Learn how to install a database and practice SQL on your own to nail take-home assignments and interview questions

04/29/2021

One day when I’m very old and crusty, and my grandchildren come to me to ask for a word of wisdom, I will look them dead in the eye and with a painful memory whisper: never... never use a dual x-axis for a column chart.

A recap of data analysis publications, guides, and news over the past month.

04/27/2021

An interesting write-up for data engineering - Kafka Is Not a Database describes the difference between streaming infrastructure and data storage: "Instead of reading and writing a traditional database, you append events to Kafka, and read from downstream views that represent the present state."

Uses and Abuses of Streaming Infrastructure