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

776 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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1 - 25 of 313 Reviews for Data Wrangling, Analysis and AB Testing with SQL

By Annie L

Feb 28, 2020

It was awful. The whole course was poorly structured or at least I couldn't understand the logic between the lessons.

Watching the videos was truly painful: I don't understand the virtues of watching someone type with all the typing noise, the countless mistakes and few proper explanation. We should have had access to slides, with the code on one side and comments on the other, such as in the previous course.

It is a unfortunate we have no access to the code in a format that could be copy-pasted neither in the instructions nor in the solutions.

On the whole, I don't really understand how such a course can be put online without more serious proof testing. Some of the instructions were out of date (using databases that were not provided) or sometimes the solutions gave results different from what we would get typing the exact same code. These problems are long reported by other learners on the forum, without being corrected.

And the final test? I found the instructions very poor: we had to do two graphs without being told what question they should answer. If I did right, these graphs did not add anything to the solution compared to a simple table. The whole test was just a replication of something seen the last week of the course ; what we were told the previous weeks was of no use at all in there. And the 'solution' does not provides the numbers needed to properly grade the works. Has no one re-read it?

By Anisha Z

Apr 3, 2020

I was quite disappointed with this course

1) They don't teach advanced SQL concepts adequately well (For example Windowing functions/Pivoting). I recommend self-learning from

2) Almost all of the content in the first 3 weeks was useless. Going through practice problems helped me learn the concepts better

3) The final assignment solution didn't match any of the the solutions I reviewed. I think the dataset has been altered, so it's impossible to get answers that match the final assignment

4) In the statistics refresher the instructor makes completely incorrect statements. For example, she says if two confidence intervals overlap then the differences are not significant. This is incorrect!

I did this so that I get the specialization certificate, but wouldn't recommend this course as a stand-alone

By Susan L

Nov 7, 2019

I liked the content of this course. It is very practical. The teaching style was frustrating for me, though. I understand that the instructor wanted us to "see" that everyone, even experts, make silly mistakes when they code (like forget ,'s or the mis-name variables), but watching mistakes being made in EVERY solutions video was too much. More time should have been taken explaining the coding concepts, rather than watching mistakes.

Also, there wasn't much discussion. I had trouble with some of the early assignments and (as instructed) asked for help in the discussion. But no one EVER responded! So I stopped asking for help. Basically, everyone just wrote "done" or something like that. To be fair, I'm not sure anyone actually looked at or read the discussion threads. You just had to write something in the discussion box to unlock the solutions video.

There also seemed to be some errors in the solution codes. Some of the solutions were fine, but others spawned errors when I cut and pasted them into Mode (the software we used). I still don't understand in one of the final assignments how the instructor used the table dsv1069.events_big (or something like that that wasn't listed as one of the files we had access to). When I tried using this file in my own code, I got an error. When I cut and pasted the entire solution code, I got an error. Maybe I was doing something wrong. I just don't know. But gaining this understanding was something I really wanted to learn …

By Marie-Eve J

Feb 11, 2020

There is a big gap between what was taught in the previous class and what is expected to be known in this class. Moreover, the instructor often poorly explains the codes that she is teaching in the solution videos. and don't seem to have been critically reviewed for improvements.

By Michael P

Aug 31, 2020

Lots of "oh wait, let me catch my own mistakes" on the videos. It appears to be sloppy, rather than a "teaching moment" for how one might debug the query.

By Alex B

Feb 3, 2020

this was the worst one I've taken on coursera. I couldn't really concentrate on what the instructor talks about in the video because I had to listen how she slams the keys while typing the code. Seriously? Couldn't that part have been muted out? This was a very bad experience. I'm going to have to take a different course on SQL AB testing

By Claire H

Apr 27, 2020

No structure to course. Very difficult to follow. No clear flow to the course. Poor explanations.

Some databases in videos no longer exist. For example, in exercise 1.4, week 1, the database dsv1069.raw_events does not exist.

It's a pity that the lectures were not available as pdf slides.

It was frustrating that the code to the solutions was not readily available in a copy and paste format.

I would expect a higher standard from Coursera especially as I PAID for the certification for this course. I feel I have not learned anything from this course just pure frustration!!

I've decided to discontinue with this course.

By Sanija K

Jan 5, 2020

Awful explanation. No structure.

By Jamison C

Oct 22, 2020

Full disclosure upfront: I did not finish this course.

Benefits: Learning about Mode as an online platform for practicing SQL with a variety of practice databases. The use cases seem potentially useful and provide some meaning and purpose to exercises. I would instead recommend you visit independently and simply save money and time by not taking this course.

Criticisms: I teach R for data science and have designed several tutorials and graduate-level courses. This involves deliberate exercises in empathy to understand where a student may begin, what resources she or he may need, varying levels of granularity in lectures, and a logical order in which to learn new material.

This course seems entirely bereft of an pedagogical rigor, by any definition. It is a salad of awkwardly narrated screen casts and the occasional slide, along with bumbling walkthroughs of solutions (some of which failed). I had to stop the course as the content literally made me uncomfortable.

As an instructor, I'm never this harsh in providing feedback either to students or fellow instructors, but as a customer, it would be unethical to stay silent. Avoid the dreadfulness and seek another course. UC Davis' brand is taking a hit with this course.

By Adam A

Sep 28, 2020

There is a large jump in difficulty between this and the previous course in the series, 'SQL for Data Science'. The instructor/course description don't mention that you'll be using PostgreSQL (after exclusively using Sqlite in the previous course). And an ER Diagram is not provided for you, nor even a list of Tables in the database (hosted on

Additionally, the format of this course is such that almost no actual Instruction is offered. The majority of the work is expected to be done by students independently via worksheets in the form of PDFs with screenshots of starting code (query text cannot be copy/pasted). The only Instructor led activities in Week 1 are short videos covering the Solutions to previous worksheets.

If you already have experience with PostgreSQL you may be okay, but I much prefer having more Lecture content prior to attempting large assignments. It would also be nice of the Instructor or a Course Admin were more active in the Discussion Forum so students could get feedback.

Overall I don't think this course is worth the money.

By Marston G

Apr 17, 2020

I'm leaving the course.

I don't think it was put together in a very solid structural way.

It was very difficult to follow from one thing to the next.

It would have been better had the instructor said 'we are going to use...' in future so keep that query.

I didn't really do that, so then I had to go back and forth and redo things.

By Ahmad B S

Apr 12, 2020

With respect to course provider and teaching staff, but this course if terrible in 2 ways: 1. teaching is not for students, rather than looks for seniors in same role as instructor. 2. the assignment and quizzes are not clear at all, you have to spend too much time to understand what is required to do. I hope this can be improved.

By Tianmin L

Nov 26, 2019

The solution data in the video sometimes do not match with the tasks provided

By Marcos d C

Nov 24, 2020

The worst course I've ever done in Coursera. Videos and exercises felt very low quality and put together in a rush. Half the course is trivial and brings nothing new. The other half introduces new concepts without any context and makes it very easy to get lost.

I am also unhappy with how little attention the discussion forums receive, so good luck if you need one of the organizers to solve an issue with the assignment.

By Lucy D

May 3, 2020

Quite frustrated. The content is interesting, relevant and well explained- however, if you need a hint with the assignments there is no help at all. I have been waiting two weeks now for my assignment to be graded (having to pay another month of coursera while I wait...) and no one has reviewed it yet. It is all peer reviewed which meant that when I submitted an assignment that I had found difficult, I am still no more informed as to what I did well and what I got wrong and therefore learnt very little from it. Assignment questions are confusingly phrased and I spent two days trying to complete it before another student wrote on the message board an explanation of what was actually being asked that many people had been trying to find out. At one point I had to submit my assignment knowing it was probably incorrect and that I simply did not understand what was being asked- a query which could have been explained in twenty seconds by the instructor but instead I had to submit, fail the assignment (not surprisingly) and then try again with another guess at the requirement.

By Mahmoud E I

Jan 24, 2022

Absolutely awful. This was by far the worst course I took on Coursera. There was no flow of ideas, new concepts fly out of no where. The instructor's explanation was lackluster and unclear. The structure of the course in general is a disgrace, I don't know how they though it's good idea to publish it. Not to forget the unclear assignments and their flawed solutions that don't even give the same answers when you run them on Mode. I only continued the course to complete the specialization.

By Sean G

Apr 10, 2020

I was not a big fan of the approach this class took to teaching the material. The idea of try it yourself before we show you how to is a cool concept, but me being new to the learning material meant that I had no clue where to start with any of the practice exercises. So I left a meaningless comment in my submission just to unlock the solution video so I can then begin learning.

Overall I didn't feel like there was enough context built into the solution videos to explain the process such as why certain functions, joins, etc. where used and a summary of the overall path of the solution video was absent but could have been very helpful as there is a lot covered in each video.

When looking to the forums for help, it appeared most of the posts where built around others also being confused or lost in the process.

The first course of this specialization was much more organized and provided better explanations. Hopefully the third and 4th legs follow course 1

By Lucia

Nov 27, 2020

I agree with a lot of the other reviews - the course could have been edited so that it was less sloppy. The questions weren't always worded in a way that made sense if you didn't have the lesson plan in mind.

Unrelated to the instructor, I would have also appreciated if other students were genuine about sharing knowledge with each other instead of just putting '.' in the responses - I think this is a flaw with Coursera's set-up, not the course.

Otherwise, the content seemed very real world applicable, which was great.

By Aman G

Jan 28, 2022

She is the worst teacher till now, I'hv seen on coursera . No doubt this course is poorly rated. She keeps doing and explaining things to herself. Without even bothering if the listeners are understanding or not.

By Joaquin J C

Nov 9, 2021

This course is like one of those 'Every programming tutorial' parody videos, except this one is not fun at all. First of all, we're informed halfway through the course that the RDBMS we will be using (MySQL) isn't the same as the previous course in the specialization (SQLite). Then the final assignment on Mode, doesn't run on MySQL but PostgreSQL (as indicated in the console), meaning the syntax was different! Such madness, but I'm glad I'm done with it now.

By Rohan L

Jun 28, 2020

One of the worst classes I've taken. I finished the first course, which also had issues. This being the second, had too many as well. I'm not going to waste time on an inferior course path.

This sequence has potential. The instructors make good videos. However, the practice problems need to be more clearly worded and in a better format.

By Alexandre C

Dec 12, 2019

I find the teacher very interesting.

The cases were also interesting.

Harder key concepts like windowing functions or multiple subqueries should be included in courses and not only in exercices solution videos.

By Luis F P M

Oct 8, 2020

Please, Update the requirements for this course, it's an intermediate level with a complex SQl analysis understanding for people mostly with basis about SQL only.

By Chelsey S

Jul 16, 2021

I'm highly disappointed in this course. Although, I did learn and practice a more intermediate level of SQL, I was highly disappointed videos and final assignment. As noted by others, Kat (the instructor) sometimes spends multiple minutes trying to determine why her own queries aren't running. The clicking of the keyboard is also HIGHLY annoying. I wished they took more time to think out this course before making the videos.

Also, and perhaps even more importantly, the final assignment which is done through the MODE app, does not allow you to create a link to share your work publically. You must have the BUSINESS version to share externally. On top of that, you can't even quickly get a free trial in order to share the link. MODE wants to schedule an appointment to discuss a trial before they give you access to a trial version of an upgraded version. Why would this course require a paid version of a service to do the final assignment? That seems unacceptable to not state upfront. And if it was an oversight, that is also unacceptable for a MOOC with hundreds, if not thousands of people taking the course.

By Shriti P

Jul 30, 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!