# Data analysis

Summary Statistics Tell You Little About the Big Picture. Visualizing Distributions — Darkhorse Analytics. Quantile plots can feel lighter or less cluttered than the ranked bars, but it can be harder to highlight a single data point. You can also calculate each of the 100 percentiles and plot them rather than plotting each and every point. Great for answering the question “what percent of my values are below/above a certain threshold?” Quantile plots in real life:Honestly, I’ve never seen them anywhere but in Stephen Few’s article on distributions displays. Give it a read for a much more in-depth discussion of quantile plots along with box plots, histograms, line charts and strip plots. Of course, you are not limited to any single one of these charts when exploring or communicating your data. The advantages of one plot can be leveraged against the disadvantages of another. Variations on box plots are often superimposed on other charts, rug plots combine well with histograms, rotate and mash two histograms together, and you get a population pyramid.

This list is by no means exhaustive. Exploring Histograms. Gather your data A histogram is based on a collection of data about a numeric variable. Our first step is to gather some values for that variable. The initial dataset we will consider consists of fuel consumption (in miles per gallon) from a sample of car models available in 1974 (yes, rather out of date). We can visualize the dataset as a pool of items, with each item identified by its value—which in theory lets us "see" all the items, but makes it hard to get the gestalt of the variable. What are some common values? Is there a lot of variation? Sort into an ordered list A useful first step towards describing the variable's distribution is to sort the items into a list. Draw the number line A common convention is to use a number line, on which higher values are displayed to the right and smaller (or negative) values to the left.

Add data to the number line Now, we map each item to a dot at the appropriate point along the number line. Notice the buttons at the bottom of the visualization? R Psychologist. Machine - June 2017 Preview. A Very Short History Of Data Science. The story of how data scientists became sexy is mostly the story of the coupling of the mature discipline of statistics with a very young one–computer science. The term “Data Science” has emerged only recently to specifically designate a new profession that is expected to make sense of the vast stores of big data. But making sense of data has a long history and has been discussed by scientists, statisticians, librarians, computer scientists and others for years. The following timeline traces the evolution of the term “Data Science” and its use, attempts to define it, and related terms. 1962 John W. Tukey writes in “The Future of Data Analysis”: “For a long time I thought I was a statistician, interested in inferences from the particular to the general. 1974 Peter Naur publishes Concise Survey of Computer Methods in Sweden and the United States. 1977 The International Association for Statistical Computing (IASC) is established as a Section of the ISI. 2001 William S.

May 2005 Thomas H. The data science ecosystem – Medium. Today this ecosystem exists only in a small number of large multinational IT companies and in some data-intensive sciences with large experimental projects. In scientific domains with smaller experiments and in smaller companies with a primary focus other than data, challenges related to developing and managing the data science ecosystem come in all shapes and sizes. That said, we can identify and describe some of the typical challenges, generalizable across multiple domains.

Manpower To a large extent, the major bottleneck is the lack of manpower. We have arguably enough domain scientists and software engineers, but there is a major mismatch between supply and demand in any of the remaining four roles related to data. Incentives Most data scientists, as other scientists, are trained and incentivized to do research on highly specialized domains. Finally, none of the researchers have interest in taking on the crucial data trainer role. Access Tools. A Tour of Machine Learning Algorithms. In this post, we take a tour of the most popular machine learning algorithms. It is useful to tour the main algorithms in the field to get a feeling of what methods are available. There are so many algorithms available that it can feel overwhelming when algorithm names are thrown around and you are expected to just know what they are and where they fit.

I want to give you two ways to think about and categorize the algorithms you may come across in the field. The first is a grouping of algorithms by the learning style.The second is a grouping of algorithms by similarity in form or function (like grouping similar animals together). Both approaches are useful, but we will focus in on the grouping of algorithms by similarity and go on a tour of a variety of different algorithm types. After reading this post, you will have a much better understanding of the most popular machine learning algorithms for supervised learning and how they are related. Algorithms Grouped by Learning Style 1. 2. 3. Conditional probability explained visually. A Visual explanation by Victor Powell for Setosa A conditional probability is the probability of an event, given some other event has already occurred.

In the below example, there are two possible events that can occur. A ball falling could either hit the red shelf (we'll call this event A) or hit the blue shelf (we'll call this event B) or both. If we know the statistics of these events across the entire population and then were to be given a single ball and told "this ball hit the red shelf (event A), what's the probability it also hit the blue shelf (event B)?

" we could answer this question by providing the conditional probability of B given that A occurred or P(B|A). P(B|A) = 0.500 or 50.0% If we have a ball and we know it hit the red shelf, there's a 50.0% chance it also hit the blue shelf. P(A|B) = 0.500 or 50.0% If we have a ball and we know it hit the blue shelf, there's a 50.0% chance it also hit the red shelf. actual expected count(A n ! Markov Chains explained visually. Explained Visually By Victor Powell with text by Lewis Lehe Markov chains, named after Andrey Markov, are mathematical systems that hop from one "state" (a situation or set of values) to another. For example, if you made a Markov chain model of a baby's behavior, you might include "playing," "eating", "sleeping," and "crying" as states, which together with other behaviors could form a 'state space': a list of all possible states.

A simple, two-state Markov chain is shown below. With two states (A and B) in our state space, there are 4 possible transitions (not 2, because a state can transition back into itself). Of course, real modelers don't always draw out Markov chain diagrams. If the state space adds one state, we add one row and one column, adding one cell to every existing column and row.

One use of Markov chains is to include real-world phenomena in computer simulations. One way to simulate this weather would be to just say "Half of the days are rainy. A 'Brief' History of Neural Nets and Deep Learning, Part 4 – Andrey Kurenkov's Web World. This is the fourth part in ‘A Brief History of Neural Nets and Deep Learning’. Parts 1-3 here, here, and here. In this part, we will get to the end of our story and see how deep learning emerged from the slump neural nets found themselves in by the late 90s, and the amazing state of the art results it has achieved since. “Ask anyone in machine learning what kept neural network research alive and they will probably mention one or all of these three names: Geoffrey Hinton, fellow Canadian Yoshua Bengio and Yann LeCun, of Facebook and New York University.” When you want a revolution, start with a conspiracy. “But in 2004, Hinton asked to lead a new program on neural computation.

“It was the worst possible time,” says Bengio, a professor at the Université de Montréal and co-director of the CIFAR program since it was renewed last year. “We should give (CIFAR) a lot of credit for making that gamble.” . So what was the clever way of initializing weights? . And inspire they did. . In 2012. . . .