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

780 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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76 - 100 of 316 Reviews for Data Wrangling, Analysis and AB Testing with SQL

By 林弋渝

Aug 20, 2020

Her teaching mode made me feel very irritable, and I even abandoned class for a while. Many solution videos contain uncertain factors, including many mistakes. I can't get the point very accurately.

By Sahil G

Jul 2, 2022

The way instructor explained the concepts is not upto the mark. Assignments can really never be completed based on the explanation of the concept given by the instructor.

By Abderrahmane K

Jul 16, 2022

Didn't like it at all, too complicated, bad lectures, bad mentor, unclear goals and unclear exercises, and some times bad voice even

By G M A E

Jun 26, 2020

am sorry but this course was very hard to understand , i think the content was very disjoind

By Dalvir B

Jun 1, 2022

Was presented overly complicated for the code used.

By Luke L

Dec 12, 2022

Where to begin? AVOID


+teaches you how to adapt to poor instructions, maybe


-You are navigating a relational database with no relational database and no schema, so hope you enjoy watching the poorly edited and long video given as your sole explanation.

-requires a knowledge of statistics which is not stated until the end

-requires you to graph without teaching you how

-poorly created questions, questions will be vague and often with poor grammar and incomplete sentences such as "Is this the right way this join. " Further, these questions might have unrelated sub questions that aren't revealed until you see the solutions such as asking whether or not an executable query looks correct with no context given on the question itself, only to discover that the query isn't good because it doesn't accomplish some yet unstated goal.

-you have to use mode analytics using instructions that, if I'm not mistaken, are outdated and no longer apply, so from week 1 you'll find yourself jerry rigging whatever you need and hoping its correct which

-once again if I'm not mistaken, the data in the database is updated? Thus changing the data and answers, meaning you can't know if your queries are correct without first knowing how to do the query as the solutions won't match, rendering the course redundant.

-the final project contains no instructions on how to share it, so you have to hope the peer grader can see it, which at this moment, I'm not actually sure how to share it correctly, and there are several people also struggling to share their report in the discussion forum

-the course doesn't actually teach you how to do its queries, and the course beforehand does not teach you how, such as using PARTITION OVER

-the SQL in the PDFs that you are supposed to complete, are for some ungodly reason, screenshots. Meaning you have to hand type the entire thing with no errors (which can lead to a lot of painful consequences for people who aren't SQL experts, such as the people taking this course).

By Justin M

Jan 16, 2021

This course did deal with some useful ideas; things like research design, statistical testing, and what to do with data that isn't cleanly structured. A lot of times, it was like the instructor was taking a normal day on a data science job and walking you through it.

The issue is the lack of structure to the course. Because it was like a a day on a job, there weren't explicit learning goals. Things like "Today we're going to learn how to clean messy data" isn't a learning goal. Instead, you want something like "Here are some ways in which data are messy. I'll walk you through what I do with each one."

The assignments reflect this. I can't stress enough how poorly the assignments supported my learning. The assignments were usually very vague, with instructions that I had to parse through to understand what was even required of me. Questions that just asked open-ended "Does this look right?" kind of questions? I mean... looks fine to me, but I'm literally in a beginner SQL course so what do I know? Then we watch a solutions video where the instructor writes the code to answer it. It lacks any kind of student engagement and doesn't facilitate learning at all.

It's really indicative of the lack of structure of the course. Since there aren't learning goals, there isn't any framework from which to design assignments. The information lacks context, so it doesn't seem useful until the very final assignment, when you need to have learned the A/B testing stuff (but not really anything else). The course material doesn't build together in a logical fashion. I feel like you could take the 4 modules in any order and you'd get the same out of it. This suggests that there isn't a core skill that's being developed over time, but rather a mishmash of ideas that might be useful in a data science position.

In all, I can't recommend this course. The instructor is an excellent data scientist, I'm sure. But her teaching could use some work.

By Joseph C

Dec 20, 2020

Very poor course. The information was very hard to interpret as the videos provided in the course did not give live output of the query being used or highlight the important sections that were being described. Additionally, the actions requested in the quizzes were incredibly vague and did not prompt the learner for what was actually being asked. This made it nigh impossible to complete the course as it was set up to accomplish. It did not ever even explicitly state which SQL language was being used (note it is different from the language used in the first course in the series). Finally, the crux of course was to teach AB Testing with SQL, however, it was explained in a fashion that was not clear or concise and did not demonstrate a real world sense of how it could be implemented in a work environment, how to set up an experiment, or even how it was accomplishing the task through SQL.

Hopefully it will make more sense as I go over the course from the beginning, but please be aware that this course was not well constructed and any insight that you might glean from it will require much more research on your part.

This course's concepts were not well explained, demonstrated, or executed.

Do not recommend...

By Frank P

Feb 16, 2021

I'll start by saying that the subjects you are supposed to learn are important, and if you do a lot of separate study this course might be very good for you. However, the way it is taught is poor. The content is disorganized and not explained well, leaving you to have to do separate research. I'm not one to bash students needing to do their own research, however this class offers no guidance. The first course of this specialization was great, and I've heard great things of all of the courses that follow this one. However this course is a miss.

The concepts are good but the execution is terrible. Not enough time was spent on the lectures, the examples that are worked through aren't taught properly, you're just watching the instructor do the assignment with very little good explanation.

Personally, I'd recommend this course be reworked to be more descriptive in each section. An extra 2 weeks to allow the instructor to take her time teaching the concepts is a very good idea. The homework/assignments also need to have their instructions rewritten to be more clear.

By Jannis

Apr 25, 2022

I have already completed a couple of courses on coursera and unfortunately I do not have lots of good things to say about this one. The videos did not prepare well for the practice exercises, the exercise sheets and solution videos seemed to have been set up quick and dirty and the quizzes were full of mistakes and misleading questions. But the setup and material was not the only problem. One of the main goals of the course was to show and get used to common problems you encounter when working with a new dataset. To reach this goal, an arbitrary dataset has been introduced and investigated in depth. Fair enough, but I do not think, that it is necessairy to do such an in depth investigation just to raise awareness that datasets might be messy and the use and distribution of such data must be done carefully. The methods themself will in most cases crucially depend on the dataset on the table and therefore will not generalize really well. I found it hard to believe that diving in an arbitrary dataset in depth for four weeks of my life was well spent time.

By Nathen M

May 29, 2022

I know this course is rated as 'Intermediate', but unless you know window functions, how to already AB test, can magically do things with a lack on instructions, and fully understand the ins and outs of Mode don't waste your time. The final project they dump on you is nearly impossible without a full understanding of how to write reports in mode and use the graphing feature. The course does not build on itself and makes leaps and bounds in information. They throw work at you with poor instructions and simply show you the answers after. I'd stop for the day, shut down my pc, and then the next day start the next assignment. It asks to refer to a previous assignment and they don't tell you to save your previous work. This was a total nightmere and should be removed from Coursera or completely rewritten. Just youtube : 'AB testing sql' for a better understanding.

By Ryan C D

Sep 23, 2022

Many learners over the years have reported issues submitting the final assignment (35% of grade), yet teacher has not cleared instructions up. Starter codes are a picture within a PDF instead of a .txt, so unable to "start" with "start"er code. Instructor's code demonstrations lacked comments and more details of why she is choosing the structure and functions. Only take if going for Learn SQL for Data Science Specialization.

By Judhajit S

Jul 28, 2022

The instructor is extremely knowledgable, but there are significant gaps in her expectations of the learners and the contents of the previous course. Also PostgreSQL complicates matters further!!! In brief, the course will benefit from inclusion of theory and practice of some of the fundamental SQL concepts as well as clarity in the assignments as to what is required of the learners.

By Carl L

Jul 31, 2022

Really sloppy in comparison to the previous course in this set. Lots of outdated information that does not line up whatsoever with what's being shown in the videos versus what appears in the exercises. This course needs an overhaul, I can't reccomend this course in good consience.

By Alexander V

May 31, 2022

To much of a gap from the basic course. In addition some of the information was so old the course flow made no sense. Also there was no real instruction on a lot of the assignments, and no info on building off the querys until the next week way after you had moved on from them.

By i a I

Jul 23, 2022

full of mistakes

By Robert A

Jan 15, 2023

This was a great learning experience. I saw some folks registered concern about some topics not clear, some topics addressed without introduction in the earlier course (e.g., windows). Frankly, this kind of learning is what I am used to, walking into a real class on a university campus. I am expected to dig in on my own where I don't quite get it. The advantage here is that I can just keep replaying the video, until I finally grasp the concepts completely. It took me twice to pass the final assignment. On the first round I was graded by two fellow students; one guy had no mercy, and the other one was reasonable, but the combination resulted in a score less than 80%. First time failure for me. But I went back and reworked the assignment and developed a much more firm understanding of the concepts and skills. Key point is that I am confident that I can use the skills practically and successfully in my work. Thanks!

By Silvia V V F

Nov 6, 2021

Un excelente curso , que requiere un nivel intermedio de conocimiento en SQL , como mejorar y optimizar las consultas siguiendo buenas practicas, aprender y aplicar SQL para realizar análisis de los resultados de las pruebas ab, como construir métricas adecuadas para la toma de decisiones en base a la naturaleza de los datos. Sería mejor si el instructor mejorara un poco su didáctica, hay partes que resultaron algo tediosas sobre todo en algunos ejemplos prácticos y si pudiera proporcionar más información sobre cómo diseñar y aplicar pruebas AB

By Tina G

Mar 21, 2023

It is a well thought our course that focuses on practical exercises and gives a glimpse into analyzing an e-commerce site, using subqueries to combine aggregate functions sum and count. It is a glitch to have to write anything to see the video, as everyone should be given access to the solution videos. However, very clear explanations of coding and solutions as this is somewhat intermediate course.

By Jumrus R

Mar 13, 2022

This course provides us a good SQL practice and exploration in the uses of various syntax. All this while showing us the imperfect picture of a professional. My complaints here would be some typos and that it's not very active - resulting in slow assignment peer-grading. If you look past those, however, I think this is a great course!

By Karina S

Jan 19, 2020

Great course!! I have learned a lot about how to evaluate the quality of the data received, how to problem solve with SQL when asked ambiguous business requirements, tips to do multiple selection editing in text editor (that was a great discovery!), metrics and AB testing. Highly recommended!

By Obira D

Apr 30, 2022

Very hand in detailed SQL analysis (tables, views, long sub-querries, goog intro to mode analytics platform, cleaning data, basic analysis and the fundamentals of A/B experiment tests at user, item level and results intepretaion).

Hihly recommended.

By Olabode A

Apr 23, 2021

The information in this course is very great as well as the practical part of the course. The instructor was very great and knowledgeable. Thus, I recommend this program to anyone who is interested in learning SQL queries.

By Ajith S R

Nov 25, 2021

It's perfect. The course starts from Nuts & Bolts and gradually reach the hype i.e., A/B Testing. It triggers us to explore lot about the content and resources given were astonishing. Keep up the great work.

By Endong T

Nov 8, 2020

The assignments are pretty difficult, and I think this course suits those who have advanced SQL skills and wanna use SQL to solve higher level problems. The lecturer are pretty interesting, and I enjoy that.