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Learner Reviews & Feedback for Data Wrangling, Analysis and AB Testing with SQL by University of California, Davis

773 ratings

About the Course

This course allows you to apply the SQL skills taught in “SQL for Data Science” to four increasingly complex and authentic data science inquiry case studies. We'll learn how to convert timestamps of all types to common formats and perform date/time calculations. We'll select and perform the optimal JOIN for a data science inquiry and clean data within an analysis dataset by deduping, running quality checks, backfilling, and handling nulls. We'll learn how to segment and analyze data per segment using windowing functions and use case statements to execute conditional logic to address a data science inquiry. We'll also describe how to convert a query into a scheduled job and how to insert data into a date partition. Finally, given a predictive analysis need, we'll engineer a feature from raw data using the tools and skills we've built over the course. The real-world application of these skills will give you the framework for performing the analysis of an AB test....

Top reviews


Sep 22, 2020

A good course for learning and apply sql to conduct analysis on ab testing results. Would be better if the instructor could provide more info about how to design and apply AB Testing on the customers


Jul 29, 2019

The instructor is very smart and her syllabus is very easy to follow. The real life examples are great and helps put ideas in perspective! I would definitely recommend this course and already have!

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176 - 200 of 313 Reviews for Data Wrangling, Analysis and AB Testing with SQL

By Philip L

Jul 8, 2020

Nice course, I learned a lot.

By Đàng n C

May 8, 2021

Thank you very much

By Rommy O R G

Jun 5, 2020

Good training.

By Varsha D

Nov 30, 2022


By Ainun E M

Jul 9, 2022


By Olga D

Apr 14, 2021

Unfortunately, overall I was not satisfied with the course.

Positive points: the course provides a training platform that enables the students to program. Not just theory! The suggested problems are business-related and seem like real-world problems. However

Negative points: the questions to the tasks are really not explained. There is some documentation to each, however, it is still unclear, unstructured, and often starting code contains the mistakes. The comments of the lecturer to every situation are very fuzzy and very hard to follow. Additionally, the follow-on part with the solution explanation seems completely unprepared, and improvised.

The final module intrigues with a very business-demanding task as A/B Testing, but the theory to it is poorly explained. So here I recommend reading some text book.

There was no guidance whatsoever on how to use the coding-submission platform, so be careful, as it is not straightforward how not to lose a part of the result during the final submission.

Overall, I give 3 points as this is the only course on Coursera with A/B testing tasks with SQL, so with a lot of patience and side learning one could try to solve suggested tasks and get some experience about complicated SQL code.

By Maryna

Mar 8, 2021

The Tasks and info are very interesting and what you really will need in your daily routine at work.

But, this course is a huge step from the first one, so huge, that there is, for sure, need to be another in between. It's definitely not for beginners. So much time was spend trying to understand the tasks and how to make them right. 'Cause, it's really poorly written.

And another huge minus for the Final assignment. You need to write it somewhere, that cloning Task, people need to choose Community mode, otherwise, other people can't see their report. I've spent a lot of time trying to resolve it. Interesting, that, when I tried to switch my report, it said that I need to upgrade, so I didn't have that option. Needed to make it again, from the beginning, in community mode. Plus, when I was reviewing, there were a bunch of people with the same problem (when others can't see their reports) and they haven't even understand, that there is a problem. They were just waiting.

By João S

Feb 15, 2023

This module is not easy. It lacks some better edition on videos, to remove errors when the instructor is teaching, and also give a better explanation of the queries. The questions are sometimes vague and difficult to understand what to do, and the tests have tasks with functions and statements that you see for the first time in the solution videos. At the end I struggled a lot on how to build a notebook and also a proper graph in Mode. There's no guide or explanation at all during the course about it. By the other hand, although it's a tough path, I learnt a lot about joins, aggregate functions, subqueries, AB test and I am very confident now when manipulating tables and reading codes. My suggestion to those taking this course is to copy the queries and reproduce them on mode with exhaustion, untill you understand what is going on.

By Antonina S

May 19, 2020

The idea is good - applying SQL knowledge on practice and learning some new features by doing. Although, the realisation is quite poor. I got this impression mostly due to the quality of the tasks formulation - looked raw, so it was sometimes not clear at all what to do. Quality of tests is also not at the best. A little revision would help a lot.

The instructor is nice and cheerful, has a pleasant voice.

Don't expect to learn much not by doing - very few explanations on the subject, mostly the course is about solving those ambiguous tasks (you get a pdf with tasks, then a solution video). There are concept videos aimed to help you a bit with the upcoming tasks but the key word here is 'a bit', so you should have already known the topic or google it.

By Noah M

May 10, 2020

I struggled through some of the exercises as they weren't well written, but in any case it's up the learner to get what he wants out of it in terms of learning goals. I also found it slightly annoying that Starter Code, often a page long was a picture snapshot on a PDF that the learner couldn't copy / paste. But that's part of the struggle I suppose, forced me to read through all the code and I got something out of even that.

I got a lot more confident creating tables for my specific purpose, through joins and feature engineering, the open-ended nature of the questions meant they were a useful step up from Course 1 of the Specialization.

Thanks for the course, good in conception, but execution needs to be tidied up a little.

By Itamara C

Apr 10, 2021

The instructor Katrina Glaeser is really, really good.

I wish I had some of her skills: smart, fast-thinking...

But, unfortunately, in order to make things easy (too easy), it was left outside important emphasis in the key points, or they weren't was explore the way that, I believe is suppose to be. So, for me, the course did not fulfill the purpose. I finished the course with a feeling that I could reproduce and understand what Katrina was planning. but, I could not explain what I was doing myself. I have not to doubt that she is brilliant as a Data analyst, but as an instructor did not work for me. I am still searching on Youtube how to do, understand, and how to analyze AB testing...

Best regards!

By Davide C

Dec 12, 2020

The course is really good to improve your SQL skills. I think the instructor is great and the course covers a lot of practical problems with plenty of possibilities to exercise.

Yet, the course lacks a well-defined structure. However, the main problem is that the training assignments along the course need to be improved a lot. The questions are not well explained and the exercises sheets are really poor, you have the impression that you are pushed to skip directly to the solution video. Also, the instructions for the final assignment are too vague. It's a pity because otherwise would be a really good course.

By Chris M

Sep 6, 2021

The material itself is interesting and helpful, but it is not always presented in the best way. I frequently had to start the solutions videos just to see what was being tasked, and more than once the solutions weren't possible even if you copied her exact code. She is clearly good at her actual job, but sometimes being good at something makes it hard to teach, because you take knowledge as a given. Several times we were taught things as if they were a continuation of stuff we should already know, and if you're only experience was the previous sections lesson you were lost.

By Mario P

Aug 19, 2021

The course itself presented great material but the manner in which it was taught was incredible difficult to follow along. The concept of attempting SQL practice exercises prior to learning the techniques was challenging. When compared to the first course, this second course was clunking and unstructured. Additionally, there should be better instructions on how to publicly share your mode report. There was a large number of individuals who did not share their report correctly and it delayed their final grade processing. This course needs updating.

By Katrina-Kay A

Feb 15, 2021

Let me start with the positive: my SQL skills definitely improved as a result of this course. It offered good practice for queries that are more complex than those in Course 1 in this specialisation. Having said this, this course really needs a facelift/revisit by the instructor. There are so many questions and assignments that are worded badly and have unclear instructions. I became quite frustrated about this around the halfway mark. As a general FYI: this course uses PostgreSQL and a service called Mode to compile code.

By Sunny Y Y S

Mar 30, 2020

The teaching value provided is great, and uses real life cases that I can relate to. 5/5 For that. However, it became a 3/5 stars due to the assignments not being as interactive that gives us an opportunity to write the code and have feedback from. Secondly, personal opinion, I definitely did not like there were a lot of limitations and constraints along the way to prevent myself to look in advance of the workload. Changing this would be beneficial to know what are the things to look out for during the videos.

By Brady S

Feb 5, 2021

It seems there was HUGE gap between this course and the previous one in the specialization. A lot of unaccounted for material and the difficulty jump is quite large. The structure of this course is subpar as there is no real learning; it's more or less giving you an exercise and then a VERY surface level explanation in a solutions video. However, the content is good. There is a LOT of material and it's all very useful - the exercises are almost all applicable to real world problems

By Dalton E

Dec 5, 2022

This was a huge jump from the first course, I was lost for the majority of this section. I also don't like the way the lessons are taught. You just watch the instructor play around with the coding until she gets it and then you move on. You're asked to try to do it first before even knowing what exactly to do. And even when she explains it, you're still a bit confused. I did like how even she messes up and made it known that it's normal to mess up on small things.

By Leong J J B

Jun 17, 2020

Topics and skills taught were relevant and good. However, more materials could have been given before letting us practise the practise questions ourselves. A lot of the questions needed knowledge of functions or ways of implementing SQL code that we did not learn before and it would have been helpful if this was taught to us first, rather having us learn from the solution videos.

By Oscar A

Feb 8, 2021

La profesora es agradable. Las primeros módulos son la continuación del anterior curso, se aprenden algunos comandos más. Algunos ejercicios requieren comandos que no se han visto pero en los videos de solución los muestran. Recomiendo leer bien la página de ABBA (ellos te dan el link) para entender mejor en qué consiste el AB testing. Me gustó la plataforma de Mode Analytics.

By jose c

May 24, 2020

The content of the course is very interesting, however it seems to me that it is not well structured, during the practices the objective in general is not understood, I think that the course should improve those details that not only consist of writing queries without knowing the meaning of each one of the variables that are being consulted in the different tables

By Wanda H

Feb 24, 2022

I thought this class was a continuation of the first course, but realized there was really no continuity between the two. The instructor should have explained more in depth especially when using shortcuts in Mode Analytics. I did not always understood what was happening and needed extra help. This course could be fined tuned a bit more.

By Laura M D V

Aug 9, 2020

First week was hard to follow. I felt very discourage to continue that it took me almost a week to return and do the rest of the course. It got better the next weeks. However, I think that strategies and pedagogical teaching can be improved. What I really like is when Katrina coded on lectures, it was cool to see her thinking process.

By Carolyn O

Dec 28, 2020

The instructions were frequently not clear. I often took her literally, which was not correct. Sometimes she didn't specifically state something she expected us to do. Other times, she stated it differently than what she really meant. It was a struggle. But I'm glad I gained more knowledge and practice writing queries.

By Tummala S R

Feb 3, 2022

The data set used in course is incoherent. There was issues deciphering the tables, column names, field names etc. Instructions were ambiguous at times making it even more cumbersome to deal with the exercises given as part of the course. Answers to the questions given as part of the final project need a review.