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L.V.'s Blog (83)

Big Data's Most Influential Rock Stars: 10 Must-Follow Leaders

This list of hand-picked leaders was compiled by Wojtek Aleksander, from

Other bigger lists (sometimes created by robots) can be found here and are usually based on your Klout score, which in my opinion is not accurate. The list below is truly original and I would even add, somewhat unexpected, as you won't find…


Added by L.V. on May 14, 2016 at 9:00am — No Comments

32 New External Machine Learning Resources and Updated Articles

Starred articles are candidates for the picture of the week. A comprehensive list of all past resources is found here. We are in the process of automatically categorizing them using indexation and automated tagging…


Added by L.V. on May 6, 2016 at 8:30am — No Comments

70 MongoDB Interview Questions and Answers

According to Wikipedia, MongoDB is a cross-platform document-oriented database. Classified as a NoSQL database, MongoDB avoids the traditional table-based relational database structure in favor of JSON-like documents with dynamic schemas (MongoDB calls the format BSON), making the integration of data in certain types of applications easier and faster. MongoDB is developed by MongoDB Inc. and is published as free and open-source software. MongoDB is the fourth most popular type of database…


Added by L.V. on May 3, 2016 at 9:00am — No Comments

Least enjoyable and most time consuming data science tasks

These are the findings from a CrowdFlower survey. Data preparation accounts for about 80% of the work of data scientists. Cleaning data is the least enjoyable and most time consuming data science task, according to the survey. Interestingly, when we asked the question to our data scientist, his answer was:…


Added by L.V. on April 5, 2016 at 9:30am — 1 Comment

Machine Learning Algorithm Identifies Tweets Sent Under the Influence of Alcohol

Interesting article posted recently in MIT Technology Reviews. What kind of metrics would help detect such tweets? We think the following might be useful:

  1. Local time (like late at night)
  2. Whether a picture or not is associated with the tweet
  3. Whether a link or not is associated with the tweet
  4. Number of typos for the tweet in question, compared with average for the user in question 
  5. Frequency of tweets (sudden spike) for user in…

Added by L.V. on March 18, 2016 at 6:30am — 1 Comment

Implementation of 17 classification algorithms in R

This long article with a lot of source code was posted by Suraj V Vidyadaran. Suraj is pursuing a Master in Computer Science at Temple university primarily focused in Data Science specialization. His areas of interests are  in sentiment analysis, data visualization, big data and machine learning.

This data is obtained from UCI Machine learning repository. The purpose of the…


Added by L.V. on March 13, 2016 at 9:30am — No Comments

19 Worst Mistakes at Data Science Job Interviews

This applies to many tech job interviews. But here we provide specific advice for data scientists and other professionals with a similar background. More advice is being added regularly. 

Here's the list:

  1. Not doing any research on the company prior to the interview.
  2. Not understanding whether they want to hire a…

Added by L.V. on February 29, 2016 at 8:30pm — 2 Comments

New Architecture for the Analytic Ecosystem

Great article by Mike Ferguson. Articles about the big data, AI, data science or IoT ecosystems are always popular. Many have been posted here (see screenshot below):

Sometimes, the keyword…


Added by L.V. on February 22, 2016 at 11:30am — No Comments

12 Emerging Trends in Data Analytics

Data Science Central shared its predictions for 2016. More predictions can be found here. In this article, we share Scott Mongeau's predictions. The full version of this (long) article can be found…


Added by L.V. on February 22, 2016 at 11:00am — 2 Comments

11 Important Model Evaluation Techniques Everyone Should Know

Model evaluation metrics are used to assess goodness of fit between model and data, to compare different models, in the context of model selection, and to predict how predictions (associated with a specific model and data set) are expected to be accurate. 

Confidence Interval. Confidence intervals are used to assess how reliable a statistical…


Added by L.V. on February 20, 2016 at 10:00am — 2 Comments

An Introduction to Variable and Feature Selection

Feature selection is one of the core topics in machine learning. In statistical science, it is called variable reduction or selection. Our scientist published a methodology to automate this process and efficiently handle la large number of features (called variables by statisticians). Click here for details.

Here, we mention an article published by Isabelle Guyon…


Added by L.V. on February 14, 2016 at 4:00pm — No Comments

Detecting and Visualising Clusterings Interaction Networks (And a few other cool things like Facebook)

This article focuses on cases such as Facebook and protein interaction networks. The article was written by By Paul Scherer (paulmorio) and submitted as a research paper to HackCambridge. What makes this article interesting is the fact that it compares five clustering techniques for this type of problems:

  • K Clique Percolation - A clique merging algorithm. Given a set kk, the algorithm goes on to produce kk clique clusters and merge…

Added by L.V. on February 13, 2016 at 8:00am — No Comments

50 Years of Data Science

Very interesting document, relatively recent (September 2015), authored by David Donoho (Statistics professor at Stanford) and posted on one of the MIT websites, here (41 pages, PDF). 

Below you will find the abstract and the table of content. Interestingly, Andrew Gelman and Vincent Granville (our data scientist)…


Added by L.V. on February 10, 2016 at 8:30am — No Comments

k-nearest neighbor algorithm using Python

This article was written by Natasha Latysheva. Here we publish a short version, with references to full source code in the original article

Our internal data scientist had a few questions and comments about the article:

  • The example used to illustrate the method in the source code is the famous iris…

Added by L.V. on February 6, 2016 at 6:00pm — 2 Comments

5 Unusual Ways to Find your First or Next Data Science Job

You did all the right things:

  • getting a quantitative degree from a good university,
  • or doing some internship,
  • attending a few online classes (Coursera),
  • spent a few weeks on a valuable data science boot camp or our data science apprenticeship, working on real big data - especially automating data processes -  even gained a certification (…

Added by L.V. on February 6, 2016 at 10:30am — 2 Comments

27 Best "Picture of the Week" Over the Last 12 Months

If you read our digests, you already know that each week, we publish our picture of the week. Below is a selection from the last few months. By clicking on the link associated with each image, you will find the article in which it is described, many times with details about how the image was produced. Some of these images are interactive, when viewed on the original web page.



Added by L.V. on February 5, 2016 at 9:30am — 1 Comment

Automated Linear Regression for Really, Really Big Data

What do you think about Inora, a company that advertises itself as the New Linear Regression Approach - Scalable to Big Data. Our data scientist also developed automated regression for big data, offering source code, even an Excel implementation, and comparing his results with traditional regression techniques.…


Added by L.V. on February 4, 2016 at 4:30pm — 1 Comment

The spectacular growth of Data Science, Machine Learning, Deep Learning, IoT, and AI

Here are a few fields that are experiencing tremendous growth. The links below provide hundreds of popular articles recently published about these topics.


Added by L.V. on January 30, 2016 at 8:00pm — 1 Comment

Top tech skills with $130K+ salary are data science related

Business Insider analyzed tech skills posted in job ads found on Below are the 6 data science skills found in the top 10, in terms of salary. This is in accordance with a previous study, performed using Glassdoor data (instead of Dice) to conclude that data scientist is the most promising job in 2016

  • MapReduce is a programming…

Added by L.V. on January 30, 2016 at 11:30am — No Comments

Spurious correlations: 15 examples

Sometimes a correlation means absolutely nothing, and is purely accidental (especially when you compute millions of correlations among thousands of variables) or it can be explained by confounding factors. For instance, the fact that the cost of electricity is correlated to how much people spend on education, is  explained by a confounding factor:…


Added by L.V. on January 26, 2016 at 5:30pm — 1 Comment


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