Probabilistic forecasting by Gneiting and Katzfuss (2014)

March 14, 2014
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Probabilistic forecasting by Gneiting and Katzfuss (2014)

The IJF is introducing occasional review papers on areas of forecasting. We did a whole issue in 2006 reviewing 25 years of research since the International Institute of Forecasters was established. Since then, there has been a lot of new work in application areas such as call center forecasting and electricity price forecasting. In addition, there are areas we did not cover in 2006 including new product forecasting and forecasting…

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Applied Statistics Lesson of the Day – The Independent 2-Sample t-Test with Unequal Variances (Welch’s t-Test)

Applied Statistics Lesson of the Day – The Independent 2-Sample t-Test with Unequal Variances (Welch’s t-Test)

A common problem in statistics is determining whether or not the means of 2 populations are equal.  The independent 2-sample t-test is a popular parametric method to answer this question.  (In an earlier Statistics Lesson of the Day, I discussed how data collected from a completely randomized design with 1 binary factor can be analyzed […]

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Filtering a Stationary Time Series

March 14, 2014
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In the first part of the MAT8181 course, on linear (univariate) time series, I forgot to mention an important theorem. Let  be a stationary time series, and  a sequence of real numbers such that then the time series  defined as is a stationary t...

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Text Mining Gun Deaths Data

March 13, 2014
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Text Mining Gun Deaths Data

In this post I will explore public data being collected by Slate.  I previously released code using a much early set of this data demonstrating how to turn this data into an animated map.This data began collection as a public response to the horri...

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For Everyone

March 13, 2014
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For Everyone

The World Wide Web’s birthday! (webat25.org). And a greeting address from Tim Bernetrs-Lee: ‘By working together, I believe we can …Continue reading →

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For Everyone

March 13, 2014
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For Everyone

The World Wide Web’s birthday! (webat25.org). And a greeting address from Tim Bernetrs-Lee: ‘By working together, I believe we can …Continue reading →

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An Economist’s Guide to Visualizing Data

March 13, 2014
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An Economist’s Guide to Visualizing Data

Stephen Jenkins wrote: I was thinking that you and your blog readers might be interested in “An Economist’s Guide to Visualizing Data” by Jonathan Schwabish, in the most recent Journal of Economic Perspectives (which is the American Economic Association’s main “outreach” journal in some ways). I replied: Ooh, I hate this so much! This seems […]The post An Economist’s Guide to Visualizing Data appeared first on Statistical Modeling, Causal Inference,…

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Setting the right priority

March 13, 2014
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Setting the right priority

On the sister blog, I wrote about a new report on the music industry lamenting that the hype over "Long Tail" retail has not really helped small artists (as a group). This was a tip sent by reader Patrick S....

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Get empowered to detect power howlers

March 13, 2014
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Get empowered to detect power howlers

If a test’s power to detect µ’ is low then a statistically significant result is good/lousy evidence of discrepancy µ’? Which is it? If your smoke alarm has little capability of triggering unless your house is fully ablaze, then if it has triggered, is that a strong or weak indication of a fire? Compare this insensitive […]

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Canada et al

March 13, 2014
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1. Today was the first day of our course on Bayesian methods in health economics. After my lecture on intro to health economics, Chris has given 2 lectures on Bayesian methods and their implementation in BUGS and then Richard has talked about Baye...

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Testing for trend in ARIMA models

March 12, 2014
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Testing for trend in ARIMA models

Today’s email brought this one: I was wondering if I could get your opinion on a particular problem that I have run into during the reviewing process of an article. Basically, I have an analysis where I am looking at a couple of time-series and I wanted to know if, over time there was an upward trend in the series. Inspection of the raw data suggests there is, but we…

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Software Carpentry at UVA, Redux

March 12, 2014
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Software Carpentry at UVA, Redux

Software Carpentry is an international collaboration backed by Mozilla and the Sloan Foundation comprising a team of volunteers that teach computational competence and basic programming skills to scientists. In addition to a suite of online lessons, ...

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Python: Numerical Descriptions of the Data

March 12, 2014
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Python: Numerical Descriptions of the Data

We are going to explore the basics of Statistics using Python. And we'll go through the following:Importing the data;Apply summary statistics;Other measures of variability (variance and coefficient of variation);Other measures of position (percentile a...

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More on publishing in journals

March 12, 2014
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I’m postponing today’s scheduled post (“Empirical implications of Empirical Implications of Theoretical Models”) to continue the lively discussion from yesterday, What if I were to stop publishing in journals?. An example: my papers with Basbøll Thomas Basbøll and I got into a long discussion on our blogs about business school professor Karl Weick and other […]The post More on publishing in journals appeared first on Statistical Modeling, Causal Inference, and…

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Oh no, the Leekasso….

March 12, 2014
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Oh no, the Leekasso….

An astute reader (Niels Hansen, who is visiting our department today) caught a bug in my code on Github for the Leekasso. I had: lm1 = lm(y ~ leekX) predict.lm(lm1,as.data.frame(leekX2)) Unfortunately, this meant that I was getting predictions for the … Continue reading →

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Reality check on the long tail

March 12, 2014
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Reality check on the long tail

Some time ago, there was a lot of hype about how new tech will demolish the superstar effect in entertainment sales because all the little titles in the long tail will be exposed to consumers. I recall Amazon being labeled the shiny example of a company that made profits off the long tail (as opposed to the boring top of the distribution). I still remember this graphic from Wired (link):…

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Unit root tests and ARIMA models

March 12, 2014
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Unit root tests and ARIMA models

An email I received today: I have a small problem. I have a time series called x : - If I use the default values of auto.arima(x), the best model is an ARIMA(1,0,0) - However, I tried the function ndiffs(x, test=“adf”) and ndiffs(x, test=“kpss”) as the KPSS test seems to be the default value, and the number of difference is 0 for the kpss test (consistent with the results of…

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Optimizing a function of an integral

March 12, 2014
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Optimizing a function of an integral

Last week I showed how to find parameters that maximize the integral of a certain probability density function (PDF). Because the function was a PDF, I could evaluate the integral by calling the CDF function in SAS. (Recall that the cumulative distribution function (CDF) is the integral of a PDF.) [...]

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Heuristics in Analytics

March 12, 2014
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Last week, a book -- a real, hard-cover paper-paged book -- arrived in the mail with the title:  Heuristics in Analytics:  A Practical Perspective of What Influences Our Analytic World.  The book wasn't a total surprise, because I had re...

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where did the normalising constants go?! [part 2]

March 11, 2014
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where did the normalising constants go?! [part 2]

Coming (swiftly and smoothly) back home after this wonderful and intense week in Banff, I hugged my loved ones,  quickly unpacked, ran a washing machine, and  then sat down to check where and how my reasoning was wrong. To start with, I experimented with a toy example in R: and (of course!) it produced the […]

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The myth of the myth of the myth of the hot hand

March 11, 2014
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Phil pointed me to this paper so I thought I probably better repeat what I wrote a couple years ago: 1. The effects are certainly not zero. We are not machines, and anything that can affect our expectations (for example, our success in previous tries) should affect our performance. 2. The effects I’ve seen are […]The post The myth of the myth of the myth of the hot hand appeared…

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Less wordy R

March 11, 2014
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Less wordy R

The Swarm Lab presents a nice comparison of R and Python code for a simple (read ‘one could do it in Excel’) problem. The example works, but I was surprised by how wordy the R code was and decided to check if one could easily produce a shorter version. The beginning is pretty much the […]

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HereHere: Mapping the Concerns of NY Citizens as an Iconographic Map

March 11, 2014
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HereHere: Mapping the Concerns of NY Citizens as an Iconographic Map

Here Here [herehere.co], developed by Future Social Experiences (FuSE) Labs at Microsoft Research, expresses neighborhood-specific public data by mapping it as text labels and cartoon-like iconography. The data is based on New York City's 311 non-e...

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