Tag Archives: Statistics

Discovering and understanding patterns in highly dimensional data

Dimensionality reduction is a critical component of any solution dealing with massive data collections. Being able to sift through a mountain of data efficiently in order to find the key descriptive, predictive, and explanatory features of the collection is a fundamental required capability for coping with the Big Data avalanche. Identifying the most interesting dimensions of data is especially valuable when visualizing high-dimensional (high-variety) big data.

There is a “good news, bad news” angle here. First, the bad news: the human capacity for seeing multiple dimensions is very limited: 3 or 4 dimensions are manageable; 5 or 6 dimensions are possible; but more dimensions are difficult-to-impossible to assimilate. Now for the good news: the human cognitive ability to detect patterns, anomalies, changes, or other “features” in a large complex “scene” surpasses most computer algorithms for speed and effectiveness. In this case, a “scene” refers to any small-n projection of a larger-N parameter space of variables.

In data visualization, a systematic ordered parameter sweep through an ensemble of small-n projections (scenes) is often referred to as a “grand tour”, which allows a human viewer of the visualization sequence to see quickly any patterns or trends or anomalies in the large-N parameter space. Even such “grand tours” can miss salient (explanatory) features of the data, especially when the ratio N/n is large.

Consequently, a data analytics approach that combines the best of both worlds (machine algorithms and human perception) will enable efficient and effective exploration of large high-dimensional data. One such approach is to apply Computer Vision algorithms, which are designed to emulate human perception and cognitive abilities. Another approach is to generate “interestingness metrics” that signal to the data end-user the most interesting and informative features (or combinations of features) in high-dimensional data. A specific example of the latter is latent (hidden) variable discovery.

Latent variables are not explicitly observed but are inferred from the observed features, specifically because they are the variables that deliver the all-important (but sometimes hidden) descriptive, predictive, and explanatory power of the data set. Latent variables can also be concepts that are implicitly represented by the data (e.g., the “sentiment” of the author of a social media posting).  

Because some latent variables are “observable” in the sense that they can be generated through a “yet to be discovered” mathematical combination of several of the measured variables, these are therefore an obvious example of dimension reduction for visual exploration of large high-dimensional data.

Latent (Hidden) Variable Models are used in statistics to infer variables that are not observed but are inferred from the variables that are observed. Latent variables are widely used in social science, psychology, economics, life sciences and machine learning. In machine learning, many problems involve collection of high-dimensional multivariate observations and then hypothesizing a model that explains them. In such models, the role of the latent variables is to represent properties that have not been directly observed.

After inferring the existence of latent variables, the next challenge is to understand them. This can be achieved by exploring their relationship with the observed variables (e.g., using Bayesian methods) . Several correlation measures and dimensionality reduction methods such as PCA can be used to measure those relationships. Since we don’t know in advance what relationships exist between the latent variables and the observed variables, more generalized nonparametric measures like the Maximal Information Coefficient (MIC) can be used.

MIC has become popular recently, to some extent because it provides a straightforward R-squared type of estimate to measure dependency among variables in a high-dimensional data set.  Since we don’t know in advance what a latent variable actually represents, it is not possible to predict the type of relationship that it might possess with the observed variables. Consequently, a nonparametric approach makes sense in the case of large high-dimensional data, for which the interrelationships among the many variables is a mystery. Exploring variables that possess the largest values of MIC can help us to understand the type of relationships that the latent variables have with the existing variables, thereby achieving both dimension reduction and a parameter space in which to conduct visual exploration of high-dimensional data.

The techniques described here can help data end-users to discover and understand data patterns that may lead to interesting insights within their massive data collections.

Follow Kirk Borne on Twitter @KirkDBorne

The Shuttle Challenger Disaster: Reflections and Connections to Data Science

The explosion of the space shuttle Challenger on Jan. 28, 1986, remains one of the worst accidents in the history of the American space program. Two other major fatal space program catastrophes also occurred within a few calendar days of the Shuttle Challenger disaster date: the Apollo 1 fire on January 27, 1967 that killed 3 astronauts, and the Shuttle Columbia disintegration on February 1, 2003 that killed 7 astronauts.

I shared some personal reflections of the Challenger event and its connections to data science in two articles. Here are excerpts from those two publications:

(1) Absence of Evidence is not the same as Evidence of Absence

In the era of big data, we easily forget that we haven’t yet measured everything. Even with the prevalence of data everywhere, we still haven’t collected all possible data on a particular subject. Consequently, statistical analyses should be aware of and make allowances for missing data (absence of evidence), in order to avoid biased conclusions. Conversely, “evidence of absence” is a very valuable piece of information, if you can prove it. Scientists have investigated the importance of these concepts in the evaluation of substance abuse education programs. They find that even though the distinctions between the two concepts (“evidence of absence” versus “absence of evidence “) are important, some policy decisions and societal responses to important problems should move forward anyway. This is an atypical case.

Usually the distinctions between the two concepts (Absence of Evidence versus Evidence of Absence) are significant influencers in decision-making and in the advancement of an area of research.

For example, I once suggested to a major astronomy observatory director that we create a database of things searched for (with his telescopes) but never found – the EAD: Evidence of Absence Database. He liked the idea (as a tool to help minimize redundant usage of his facilities for duplicate false searches in cases where we already have clear evidence of absence), but he didn’t offer to pay for it. Here is one science paper that has dramatically understood this concept: “Can apparent superluminal neutrino speeds be explained as a quantum weak measurement?” The paper’s full complete abstract: “Probably not.”

A more dramatic and ruinous example of a failure to appreciate this statistical concept is the NASA Shuttle Challenger disaster in 1986, when engineers assumed that the lack of evidence of O-ring failures during cold weather launches was equivalent to evidence that there would be no O-ring failure during a cold-weather launch. In this case, the consequences of faulty statistical reasoning were catastrophic. This is an extreme case that clearly demonstrates that “Absence of Evidence is not the same as Evidence of Absence” is an important statistical truism that we must never forget in the era of big data.

(read my full article at http://www.statisticsviews.com/details/feature/4911381/Statistical-Truisms-in-the-Age-of-Big-Data.html)

(2) A Growth Hacker’s Journey – At the right place at the right time

A few months after my arrival at the Hubble Telescope Science Institute in 1985, tragedy struck! In January 1986, the Shuttle Challenger exploded 78 seconds after launch, killing all 7 astronauts on board. As a young person who dreamed of working in astronomy and space sciences since I was 9 years old, I was devastated. It took weeks for the staff to recover from the trauma of that horrific day. To this day, I still get choked up when I watch the recorded video footage of the event. Three things became very clear during those after-months:

  • The Shuttle launches would not resume for several years (hence, the Hubble Telescope would be grounded for all those years) while NASA fixed the problems that led to the Challenger catastrophe, which meant that the Hubble team of scientists and engineers had a lot of years to evaluate and improve all of the telescope systems.
  • One of the systems that was in significant need of improvement was the administrator-oriented Hubble Data Management System, which was previously designed primarily for data management by data system administrators and not designed so much for scientist-friendly data access, exploration, and discovery — hence, during those post-Challenger years, fresh designs and plans were developed for a new “top of the line” scientist-oriented user-friendly Hubble Science Data Archive.
  • Another system was identified as needing total overhaul, even rewriting the entire code base from scratch, and that was the scientific proposal entry, processing, and reporting system — they needed someone new to do the job, someone with a fresh perspective, with database skills, user interface skills, programming skills, and strong familiarity with astronomy. Guess who satisfied all of those constraints?

(read my full article at https://www.mapr.com/blog/growth-hackers-journey-right-place-right-time)

Follow Kirk Borne on Twitter @KirkDBorne

big-hst

Outliers, Inliers, and Other Surprises that Fly from your Data

Data can fly beyond the bounds of our models and our expectations in surprising and interesting ways. When data fly in these ways, we often find new insights and new value about the people, products, and processes that our data sources are tracking. Here are 4 simple examples of surprises that can fly from our data:

(1) Outliers — when data points are several standard deviations from the mean of your data distribution, these are traditional data outliers. These may signal at least 3 possible causes: (a) a data measurement problem (in the sensor); (b) a data processing problem (in the data pipeline); or (c) an amazing unexpected discovery about your data items. The first two causes are data quality issues that must be addressed and repaired. The latter case (when your data fly outside the bounds of your expectations) is golden and worthy of deeper exploration.

(2) Inliers — sometimes your data have constraints (business rules) that are inviolable (e.g., Fraction of customers that are Male + Fraction of customers that are Female = 1). A simple business example would be: Profit = Revenue minus Costs. Suppose an analyst examines these 3 numbers (Profit, Revenue, Costs) for many different entries in his business database, and he finds a data entry that is near the mean of the distribution for each of those 3 numbers. It appears (at first glance) that this entry is perfectly normal (an inlier, not an outlier), but in fact it might violate the above business rule. In that case, there is definitely a problem with these numbers — they have “flown” outside the bounds of the business rule.

(3) Nonlinear correlations — fitting a curve y=F(x) through data for the purpose of estimating values of y for new values of x is called regression. This is also an example of Predictive Analytics (we can predict future values based upon a function that was learned from the historical training data). When using higher-order functions for F(x) (especially polynomial functions), we must remember that the curves often diverge (to extreme values) beyond the range of the known data points that were used to learn the function. Such an extrapolation of the regression curve could lead to predictive outcomes that make no sense, because they fly far beyond reasonable values of our data parameters.

(4) Uplift — when two events occur together more frequently than you would expect from random chance, then their mutual dependence causes uplift. Statistical lift is simply measured by: P(X,Y)/[P(X)P(Y)]. The numerator P(X,Y) represents the joint frequency of two events X and Y co-occurring simultaneously. The denominator represents the probability that the two events X and Y will co-occur (at the same time) at random. If X and Y are completely independent events, then the numerator will equal the denominator – in that case (mutual independence), the uplift equals 1 (i.e., no lift). Conversely, if there is a higher than random co-occurrence of X and Y, then the statistical lift flies to values that are greater than 1 — that’s uplift! And that’s interesting. Cases with significant uplift can be marketing gold for your organization: in customer recommendation engines, in fraud detection, in targeted marketing campaigns, in community detection within social networks, or in mining electronic health records for adverse drug interactions and side effects.

These and other such instances of high-flying data are increasingly challenging to identify in the era of big data: high volume and high variety produce big computational challenges in searching for data that fly in interesting directions (especially in complex high-dimensional data sets). To achieve efficient and effective discovery in these cases, fast automatic statistical modeling can help. For this purpose, I recommend that you check out the analytics solutions from the fast automatic modeling folks at http://soft10ware.com/.

The Soft10 software package is trained to report automatically the most significant, informative and interesting dependencies in your data, no matter which way the data fly.

(Read the full blog, with more details for the 4 cases listed above, at: https://www.linkedin.com/pulse/when-data-fly-kirk-borne)

Follow Kirk Borne on Twitter @KirkDBorne

Reach Analytics Maturity through Fast Automatic Modeling

The late great baseball legend Yogi Berra was credited with saying this gem: “The future ain’t what it used to be.” In the context of big data analytics, I am now inclined to believe that Yogi was very insightful — his statement is an excellent description of Prescriptive Analytics.

Prescriptive Analytics goes beyond Descriptive and Predictive Analytics in the maturity framework of analytics. “Descriptive” analytics delivers hindsight (telling you what did happen, by generating reports from your databases), and “predictive” delivers foresight (telling you what will happen, through machine learning algorithms). Going one better, “prescriptive” delivers insight: discovering so much about your application domain (from your collection of big data and information resources, through data science and predictive models) that you are now able to take the actions (e.g., set the conditions and parameters) needed to achieve a prescribed (better, optimal, desired) outcome.

So, if predictive analytics can use historical training data sets to tell us what will happen in the future (e.g., which products a customer will buy; where and when your supply chain will need replenishing; which vehicles in your corporate fleet will need repairs; which machines in your manufacturing plant will need maintenance; or which servers in your data center will fail), then prescriptive analytics can alter that future (i.e., the future ain’t what it used to be).

When dealing with large high-variety data sets, with many features and measured attributes, it is often difficult to build accurate models that are generally useful under a variety of conditions and that capture all of the complexities of the response functions and explanatory variables within your business application. In such cases, fast automatic modeling tools are needed. These tools can help to identify the minimum viable feature set for accurate predictive and prescriptive modeling. For this purpose, I recommend that you check out the analytics solutions from the fast automatic modeling folks at http://soft10ware.com/.

The Soft10 software package is trained to observe quickly and report automatically the most significant, informative and explanatory dependencies in your data. Those capabilities are the “secret sauce” in insightful prescriptive analytics, and they coincide nicely with another insightful quote from Yogi Berra: “You can observe a lot by just watching.”

(Read the full blog at: https://www.linkedin.com/pulse/prescriptive-analytics-future-aint-what-used-kirk-borne)

Predictive versus Prescriptive Analytics

Predictive Analytics (given X, find Y) vs. Prescriptive Analytics (given Y, find X)

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Blogging My Way Through Data Science, Big Data, and Analytics

I frequently write blog posts on other sites.  You can find those articles here (updated March 21, 2016):

I also write “one-off” blog posts, such as these examples:

Follow Kirk Borne on Twitter @KirkDBorne

A Day in the Life of Confounding Factors and Explanatory Variables

Would we trust an insurance provider who sets motorbike insurance rates based on the sales of sour cream? Or would we schedule our space launches according to the number of doctoral degrees awarded in Sociology?

Probably all of us would agree that this kind of decision-making is unjustified. A specific decision like this appears to be only superficially supported by the evidence of correlations between those various factors, but is there more to the story? Does it go any deeper? What if there exists a hidden causal factor that induces the apparently spurious correlation?

For example, suppose the increase in space launches and the increase in doctoral degrees in Sociology were both related to an increase in government investments in research studies on the sociological impacts of establishing a permanent human colony on the Moon. This case reveals a hidden causal connection in an otherwise strange correlation. The explanatory variable (which is a hidden confounding factor) is the research investment, and the response variables are the space launches and doctoral degrees.

What about other cases? What about the evidence that sour cream sales correlate with motorbike accidents? In such cases, shouldn’t we all be pleased to see organizations making evidence-based data-driven objective decisions (especially in this brave new world of exploding data volumes and ubiquitous analytics)? No, I don’t think so!!

So, what kind of world is this?

Welcome to the world of explanatory variables and confounding factors!

Statistical literacy is needed now more than ever (to paraphrase H. G. Wells). This includes awareness of and adherence to common principles of statistical reasoning. For example…

(continue reading here http://www.statisticsviews.com/details/feature/7914611/A-Day-in-the-Life-of-Explanatory-Variables-and-Confounding-Factors.html)

Follow Kirk Borne on Twitter @KirkDBorne

The Definitive Q&A for Aspiring Data Scientists

I was recently asked five questions by Alex Woodie of Datanami for the article, “So You Want To Be A Data Scientist” that he was preparing. He used a few snippets from my full set of answers. The longer version of my answers provided additional advice. For aspiring data scientists of all ages, I provide here the full, unabridged version of my answers, which may help you even more to achieve your goal. (Note: I paraphrase Alex’s original questions in quotes below.)

1. “What is the number one piece of advice you give to aspiring data scientists?”

My number one piece of advice always is to follow your passions first. Know what you are good at and what you care about, and pursue that. So, you might be good at math, or programming, or data manipulation, or problem solving, or communications (data journalism), or whatever. You can do that flavor of data science within the context of any domain: scientific research, government, media communications, marketing, business, healthcare, finance, cybersecurity, law enforcement, manufacturing, transportation, or whatever. As a successful data scientist, your day can begin and end with you counting your blessings that you are living your dream by solving real-world problems with data. I saw a quote recently that summarizes this: “If you think your scarce data science skills could be better used elsewhere, be bold and make the move.” (Reference).

2. “What are the most important skills for an aspiring data scientist to acquire?”

There are many skills under the umbrella of data science, and we should not expect any one single person to be a master of them all. The best solution to the data science talent shortage is a team of data scientists. So I suggest…

(continue reading herehttps://www.mapr.com/blog/definitive-qa-aspiring-data-scientists)

Follow Kirk Borne on Twitter @KirkDBorne

Clear and Obvious Analytics for Clear and Present Dangers

Not every industry has found their clear and obvious applications of big data analytics. But the clear and present dangers of risk and fraud in financial transactions demand fast predictive modeling. Precisely because we live in the ubiquitous digital era, where most business (and non-business) transactions are rarely (if ever) in analog form and those transactions no longer move at the pace of humans (but at the speed of light), consequently the volume of digital signals as well as lurking dangers is enormous.

Digital signals (from sensors everywhere in our operational business systems) carry transactional information (what happened to what?), as well as metadata (descriptors) and analytics information (data-encoded knowledge and insights).  These analytics can be behavioral (providing insights into the interests, intentions, and preferences of the actors in a given transaction) as well as functional (providing insights into the actions or events associated with the transaction).

Behavioral analytics is developing into a major component of digital marketing, as firms seek to sell, cross-sell, and up-sell their products to the right customer at the right time.  Behavioral analytics is also critical in risk mitigation of all sorts: financial, cybersecurity, health (individual and population), supply chain, machine performance, and so on.

Here are 10 examples of where fast predictive analytics can play a vital role in most industries (with a focus on financial):

  1. Predict credit risk and fraud in real-time!
  2. Use Social Media for deeper understanding (likes and dislikes) of your customers.
  3. Personalize customer interactions in real-time, across multiple channels.
  4. Stop improper insurance payments before claims are paid!
  5. Spot insurance rate evasion tactics during the quote process – before you issue a policy!
  6. Predict High Health Risk versus Low Health Risk to better manage healthcare decision-making.
  7. Generate better predictive models of health, car, and home insurance eligibility fraud, underwriting fraud, and improper payments.
  8. Spot adversarial and anomalous behavior in cyber networks – stop the data breach or illegal funds transfer before it happens!
  9. Eliminate your Supply Chain hiccups – move the right products to the right locations in the right quantities – and at the right time!
  10. Make better business decisions regarding merchandising, demand forecasting, and pricing – don’t leave money on the table, or products in your warehouse.

Let us look a little more closely at the financial services industry…

One of the common conditions in traditional financial services (including home, health, and auto insurance) has been the “pay and chase” — i.e., you make the payment to the claimant, and then (after making the payment) you find out that the claim is fraudulent, thus beginning the chase to get your money back.

The new world of predictive modeling and advanced analytics allows for a new mantra in the financial and insurance industries: “Do Not Pay!” — i.e., you do not pay the claim until you have analyzed its likelihood for claim fraud, extraordinary financial risk, or payment anomalies (e.g., duplicate payments).

Predictive analytics modeling delivers a better financial risk posture for your organization than the “pay and chase”. With access to greater and more diverse data sources, it is now possible to develop better models of your customers’ credit risk regardless of the industry. This is certainly true in the financial services industry where there is so much data available: credit scores, credit history, court records, tax records, health records, insurance claims, and more. There is no excuse for not examining as much “public data” as you can in conjunction with other data sources that are available to you internally within your organization. Moderate outlays of your organization’s funds that are incurred in acquiring access to diverse external data sources should be offset by the savings accrued by “not sending your funds out the door” erroneously (either to intentional fraudsters or in unintentional duplicate claims).

An analytics-driven predictive model can predict fraud more efficiently (with fast automatic statistical software packages) and more effectively (with higher precision and higher recall: fewer false positives and false negatives) than traditional business processes. A good predictive analytics model should: (a) detect claims that “smell funny”, (b) prevent the “pay and chase” mode of operations, and (c) stop claims fraud abruptly by empowering a “do not pay” mode of operations. Predictive analytics modeling should aim to satisfy the following business requirements:

  • Detect and prevent both opportunistic and professional fraud throughout the claims process.
  • Detect underwriting fraud, to prevent premium leakage at the point of sale and renewal.
  • Spot rate evasion tactics during the quote process – before you issue a policy.

Many more examples of use cases in the financial services industry (and elsewhere) where fast predictive analytics is important (and what you can do about it) have been expertly enumerated by the fast statistical modeling folks from Soft10, Inc. Check out their fast analytics products (including the Instant Online Overbilling Claims Detector) at http://soft10ware.com/.

Follow Kirk Borne on Twitter @KirkDBorne

These are a few of my favorite things… in Big Data and Data Science: A to Z

A while back, we made a list from A to Z of a few of our favorite things in big data and data science. We have made a lot of progress toward covering several of these topics. Here’s a handy list of the write-ups that I have completed so far:

AAssociation rule mining:  described in the article “Association Rule Mining – Not Your Typical Data Science Algorithm.”

C – Characterization:  described in the article “The Big C of Big Data: Top 8 Reasons that Characterization is ‘ROIght’ for Your Data.”

H – Hadoop (of course!):  described in the article “H is for Hadoop, along with a Huge Heap of Helpful Big Data Capabilities.” To learn more, check out the Executive’s Guide to Big Data and Apache Hadoop, available as a free download from MapR.

K – K-anything in data mining:  described in the article “The K’s of Data Mining – Great Things Come in Pairs.”

L – Local linear embedding (LLE):  is described in detail in the blog post series “When Big Data Goes Local, Small Data Gets Big – Part 1” and “Part 2

N – Novelty detection (also known as “Surprise Discovery”):  described in the articles “Outlier Detection Gets a Makeover – Surprise Discovery in Scientific Big Data” and “N is for Novelty Detection…” To learn more, check out the book Practical Machine Learning: A New Look at Anomaly Detection, available as a free download from MapR.

P – Profiling (specifically, data profiling):  described in the article “Data Profiling – Four Steps to Knowing Your Big Data.”

Q – Quantified and Tracked:  described in the article “Big Data is Everything, Quantified and Tracked: What this Means for You.”

R – Recommender engines:  described in two articles: “Design Patterns for Recommendation Systems – Everyone Wants a Pony” and “Personalization – It’s Not Just for Hamburgers Anymore.” To learn more, check out the book Practical Machine Learning: Innovations in Recommendation, available as a free download from MapR.

S – SVM (Support Vector Machines):  described in the article “The Importance of Location in Real Estate, Weather, and Machine Learning.”

Z – Zero bias, Zero variance:  described in the article “Statistical Truisms in the Age of Big Data.”

The Goldilocks Principle in Predictive Modeling and Data Science

In the field of statistics, there has been a lot written about statistical fallacies, logical fallacies, and fallacious reasoning. The following big list of fallacies is one that I like to use in my own undergraduate data science courses, particularly in my Data Ethics class where I teach my students about “lying with statistics”:

http://en.wikipedia.org/wiki/List_of_fallacies

Many of these fallacies are relevant to data science modeling, including this one: Circular Reasoning, where the reasoner “begins with what he or she is trying to end up with; sometimes called assuming the conclusion.”

A broken clock is truly an example of circular reasoning (as the dial is circular, and the clock represents a particular measurement in a repeating circular perspective): “Even a broken clock is right twice a day.”

(source: http://tvtropes.org/pmwiki/pmwiki.php/Main/StoppedClock)

In the following article, I use the broken clock analogy for circular reasoning in describing the importance of verification and validation in predictive analytics models: Are your predictive models like broken clocks? Here’s how to fix them.”  The article also discusses the importance of training vs. test data sets, the bias-variance tradeoff in data science modeling, underfitting vs. overfitting, and the Goldilocks Principle applied to data science.

(continue reading here) 

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