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Learner Reviews & Feedback for Getting and Cleaning Data by Johns Hopkins University

8,004 ratings

About the Course

Before you can work with data you have to get some. This course will cover the basic ways that data can be obtained. The course will cover obtaining data from the web, from APIs, from databases and from colleagues in various formats. It will also cover the basics of data cleaning and how to make data “tidy”. Tidy data dramatically speed downstream data analysis tasks. The course will also cover the components of a complete data set including raw data, processing instructions, codebooks, and processed data. The course will cover the basics needed for collecting, cleaning, and sharing data....

Top reviews


May 2, 2020

This course provides an introduction of some important concepts and tools on a very important aspect of data science: cleaning and organizing data before any analysis. A must for any data scientist.


Oct 25, 2016

This course is really a challenging and compulsory for any one who wants to be a data scientist or working in any sort of data. It teaches you how to make very palatable data-set fro ma messy data.

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1251 - 1275 of 1,296 Reviews for Getting and Cleaning Data

By Maximilian P

Jul 11, 2018

Too many things in one place

By Sergio B

Nov 17, 2017

Worst class in this series.

By Michal K

Apr 29, 2016

too superficial

By Leandro J G D

May 12, 2020

Lacking focus.

By Warren

Aug 5, 2016


By Walson Q

Nov 29, 2018


By Andrea C

Jan 22, 2023

Unfortunately this course had lots of potential but it turns out to have just a lot of flaws. The material presented is so dense that it would have needed a much more detailed discussion: getting data from the web in CVS format, XML, JSON, databases, etc. All these different aspects should have been discussed in much more detail.

The second and most important flaw is the fact that virtually all data are out of date, and it is often impossible to follow along with the code, because the data is no longer available. Since the material presented is so much, it would have been useful to follow along, keeping the code for further analysis and for understanding what is actually going on, but that has not been the case, which is very disappointing.

Finally, some of the packages, like plyr, are presented so quickly and the code explained sometimes doesn't work as expected. Another example is xlsx, that does not work with MAC and requires some personal google research to fix the issues. I had lots of expectation for this course, as I was curious to understand better data scraping and the link between R and databases, but the course has been a total disappointment. Once I have finished the specialisation, I will have to find some other courses to complement this, which is also extremely disappointing. From such a prestigious university, I'm afraid I had expected more.

By Dan H

Jan 16, 2018

This course is about getting data from the web and processing it using a computer language and packages in that language that are under active development. There is a github repo with course content and other electronic resources that are made to be easy to update. It has never been updated, even once since the course first went live 4 years ago. There are many broken links, several new features and bugs in packages that make lecture content obsolete or broken, errors found by students, etc. None of these issues have been addressed, even once, in any of the material, including the extremely easy to update content on github. This is disappointing and not very professional. Additionally, many of the notes are not particularly good to begin with. Much of it is essentially cribbed from other online tutorials, examples in the documentation, and in a few cases, someone else's (also broken) lectures. Take this course if you want a study group (the forums are actually quite useful) to help you go through 4 year old lectures rehashing online tutorials from 4 years ago about a topic that changes pretty quickly.

By Grant I

Jan 22, 2018

Made it all the way to week four and decided to drop this entire specialization. The data set in the final project is poorly referenced (despite the code book provided). The data set comes in 24 text files you have to merge (which isn't a problem in R) but what is a problem is when you don't understand what the variables and observations are. Perhaps if I worked in the medical field these measurements would mean more, but to a business major, they are incomprehensible with the limited documentation provided. So my assumption was, if I am having difficulty understanding what the final data structure should look like, others will be having the same problem......and its peer reviewed. How can I possible grade someone else

By Abdulaziz M A A

Jul 2, 2020

I have to date completed the first 2 courses in Data Science: Foundations using R Specialization.

Today I have cancelled my subscription for the following reasons:

1 Poor course design and delivery

Lesson contents inadequately covered and sourced, lecturers deliver a fast paced recordings with very little examples and references making it hard for beginner students to keep pace and find themselves unprepared for the required quizzes and exams.

2 Course materials needs to be updated and presented to facilitate learning , eg. often times students are referred to static links and too many many times new and un-familiar concepts/ functions are rushed thru with no introduction or explanation.

By Ryan N

Oct 29, 2021

Course content is ok except for the week 2, quite confusing. Not very detail. Quite a few slides asking you to read up yourself from other sources.

And for the quizzes, mostly beyond the scope of the course.

Project wise, coding part is fine. The part that is totally not fine is the project requires you to prepare codebook and README, without any guidance in any videos in this course, or courses prior to taking this course. All you need is to read up yourself from other sources. The community are assuming people who are taking these courses have good knowledge in programming related work.

By Apurva G

Mar 30, 2020

Its extremely difficult to install the packages. Most of the time the instructions are not clear on what packages to intall in the videos. There should be a pre-read with links and instructions on which packages are needed to be able to work on this course. Extremely frustrating, considering a majority of the time is wasted just trying to figure out how to install packages. If you are serious about success of course takers, you have to make it easier to understand and instructions have to be clear.

By Andrés P

Jun 22, 2022

I received my certificate and it states the following:

"This certificate does not af_rm that this learner was enrolled as a student at Johns Hopkins University. It does not confer a JHU grade, course credit or degree; establish a relationship between this learner and JHU; enroll or register this learner at JHU or in any course offered by JHU; or entitle this learner to access or use resources beyond the online courses provided by Coursera."

Does this mean has no validation?

By Zdeněk Š

Aug 27, 2022

The peer review is very frustrating. Sometimes the peers appear to not understand the assignment and you cant contest the decision. Many reviewers write only "you can do better" as they give you low scoring, with no further explanation of whats wrong.

The information taught in this course is equivalent to a couple of tutorials you can find online for free, paying for this is a waste of money. Sadly, having certificates looks good, even if they mean nothing.

By Deleted A

Jan 13, 2017

For such a terrible course to then change payment terms without my authorisation. Take $64 from my account without telling me clearly amongst all the other junk mail. Coursera have a lot to answer for, and this specialisation is not even worth wasting your time if it was free.

Taught without purpose; meaningless instructions given to copy without regard of the bigger picture.

By Quoc N

Feb 18, 2018

First quiz states 10 minutes for a 5 question quiz. I am taking way longer due to errors in loading packages and Java. One of the question is out of date and has not been updated in a year. Quality of this course is lacking when changes are constant. The mentors say it's realistic. I'd considering dropping this course and search for a better updated one.

By Daniel L

Feb 7, 2021

Packages and code shown is outdated, different file formats are shown very briefly, without any attempt to communicate understanding. If I have to reproduce code that does not work and then spend hours googling solutions to problems I would not have if this course was done properly, I prefer not doing the course at all. Waste of time.

By Pooia L

Aug 19, 2018

This was a mix of everything course, nothing was completely explained. It would have been a better idea to just pick a limited options and cover them well. The description of the final project was a puzzle and the objective behind it was completely vague. I wanted to quit in the middle, but I put time and that is why I finished it!!!

By Antti S

Oct 17, 2016

Lectures and other material just don't cover the information needed in the course project. Majority of the learning has to be done outside of this course, in order to pass the course project.

I cannot recommend this course anyone who is not deeply familiar with the topic already. The course project is truly frustrating!

By Shanmuga P

Jan 14, 2018

Expected more explanation with the teaching part, detailed lecture depicting live examples is needed to explain each and every module of the course. similar examples like Assignments can be taught by hard-coding them with RStudio

hoping that these things can change with the next courses which I'm enrolling

By Diogo M

Aug 6, 2018

MUito rápido o conteúdo e o fato do suporte ser somente o fórum deixa o curso vago, achei muito fraco os slides e o método de ensino.

Poderiam focar mais em exercícios e nos comandos mais difíceis, pois quando chega nos assignments fiquei perdido por não ter conseguido realizar da forma esperada.

By Michael O

Oct 29, 2016

Basically impossible to complete quizzes and course project using the provided course material. Poor correlation between instruction and testing. Makes one wonder: If I need to solicit others' guidance to complete your tests, why am I paying for your guidance in the first place?

By Borin S

Oct 24, 2022

The swirl package can't be loaded due to old dependencies, so do the course; using very old version of R.

The lectures are very hard to follow as the examples in videos removed from web. which was very disappointing.

By Jeffrey G

Jul 6, 2017

Why are people writing extensive blog posts contemplating the vague wording of the final assignment when you could just *fix the assignment*? Also, one of the worst explanations of regular expressions I've ever heard.

By Jan-Willem A

Mar 15, 2016

There are quite a few issues with the final assignment of the Getting and Cleaning Data course. I feel this assignments lacks quality in contents, suffers from a flawed process and lack of attention by the moderator.