Archive

Archive for the ‘infos’ Category

R 2.11.0 due date

This is the announcement as posted in the mailing list :

This is to announce that we plan to release R version 2.11.0 on Thursday,
April 22, 2010.

Those directly involved should review the generic schedule at
http://developer.r-project.org/release-checklist.html

The source tarballs will be made available daily (barring build
troubles) via
http://cran.r-project.org/src/base-prerelease/

For the R Core Team
Peter Dalgaard
Advertisements
Categories: infos Tags: , , ,

Oh, mr counselor!

Xm…

There were two men trying to decide what to do for a living.  They went to see a counselor, and he decided that they had good problem solving skills.

He tried a test to narrow the area of specialty.  He put each man in a room with a stove, a table, and a pot of water on the table.  He said “Boil the water”.  Both men moved the pot from the table to the stove and turned on the burner to boil the water.  Next, he put them into a room with a stove, a table, and a pot of water on the floor.  Again, he said “Boil the water”.  The first man put the pot on the stove and turned on the burner.  The counselor told him to be an Engineer, because he could solve each problem individually.  The second man moved the pot from the floor to the table, and then moved the pot from the table to the stove and turned on the burner.  The counselor told him to be a mathematician because he reduced the problem to a previously solved problem.

– From The Mathematician, The Physicist and The Engineer (and Others)

Categories: infos Tags: , , , , ,

A normal philosophy…

The following was sent by email to me. It originates to Youden.

                                 THE
                                NORMAL
                             LAW OF ERROR
                           STANDS OUT IN THE
                         EXPERIENCE OF MANKIND
                        AS ONE OF  THE BROADEST
                       GENERALIZATIONS OF NATURAL
                     PHILOSOPHY . IT SERVES AS THE
                   GUIDING INSTRUMENT IN RESEARCHES
                IN THE PHYSICAL AND SOCIAL SCIENCES AND
               IN MEDICINE AGRICULTURE AND ENGINEERING .
          IT IS AN INDISPENSABLE TOOL FOR THE ANALYSIS AND THE
INTERPRETATION OF THE BASIC DATA OBTAINED BY OBSERVATION AND EXPERIMENT

–W.J. Youden

Youden is one of the truly inspiring statisticians to me.

Categories: infos Tags: , ,

Thou shalt…(could do better with the title,huh?)

February 26, 2010 Leave a comment

Are these the ten commandments? MacIntyre, P.D., serves as Moses of our industry… 😉

I. Get as large a sample as you can.
A. Large N provides for more stable measurement of variables, they are less likely to be affected by outliers.
B. Large N also provides for distributions that are more normal, or better reflect the full range of scores in the population.

II. Run as few statistical tests as you can.
A. running several tests increase the risk of a Type 1 error
B. focus your results as much as possible

III. Never report the same data twice.
A. all of the statistics you have learned are part of the same model, thus if one test is significant (e.g., correlation) then a different statistic will also be (e.g., regression).
B. when doing tests of means following ANOVA, especially for analysis of interactions, include each mean in only 1 test (if possible).

IV. When using multivariate tests, always get the most for the least.
A. in factor analysis, account for high percentage of variance with as few factors as possible.
B. in multiple regression, get the highest R2 with the fewest predictors.
C. in path analysis, specify as few paths as possible that account for most of the correlations

V. Use the most reliable measures possible.
A. always test for the reliability of scales or multi-item tests before computing a total score for the test.
B. if a variable is unreliable, its correlations with other variables are almost always lower than they should be. Thus, you underestimate the true degree of correlation but you don’t know by how much.

VI. Plan your analysis before collecting the data.
A. there are some studies whose data cannot be analyzed because the analyses were not planned in advance.
B. control for potential problems when designing the study, not when analyzing the data.

VII. Use statistics to support the written (verbal) argument, not to substitute for it.
A. also, do not write statistics that you don’t understand, it shows.

VIII. Never do multiple tests without controlling for Type 1 error.
A. never do several t-tests when ANOVA is appropriate
B. never do several ANOVAs when MANOVA is appropriate
C. never do post hoc t-tests or many correlations without adjusting alpha (or at least admitting to the risk of Type 1 error when writing them up)

IX. Never try to prove the null hypothesis.
A. do not design a study to show “no difference” between means or “no correlation” between variables.

X. Others
A. Never trust a factor with less than three substantial loadings.
B. Never interpret a correlation without looking at the scatterplot
C. Look for outliers but never toss them out unless you know that the data are inaccurate
D. Don’t tug on superman’s cape, spit into the wind, offer to pet a porcupine, or walk downtown with a live duck on your head.

Categories: infos

PoRtable…

February 24, 2010 Leave a comment

Jobless as I might be, I do have some clients for data analysis. I try not to visit them in their office coz then things get really slow and time-consuming. When I can’t escape this, the worst thing is tuning data and software with client. So, I have a USB with portable versions of my toolbox. Yesterday, I installed R and today I tested it. It worked fine!

If you want to try it, download the software platform from here. Install it (when prompt to extract/unzip) into a file in your USB, ie /OS, and then download the R portable from here. From the portable OS menu (down-right on your screen) select install software and browse to the R portable file. After a couple of minutes you’re done!


Special thanks to Andrew Redd for providing us with the portable version.

Categories: infos Tags: , ,

A normal valentine’s day approach…

February 14, 2010 Leave a comment

[source]

Categories: infos Tags: ,

What is(n’t) a statistician…

February 11, 2010 1 comment

The minute a statistician steps into the position of the executive who must make decisions and defend them, the statistician ceases to be a statistician.

Dr. W. Edwards Deming is known as the father of the Japanese post-war industrial revival and was regarded by many as the leading quality guru in the United States. He passed on in 1993.

Trained as a statistician, his expertise was used during World War II to assist the United States in its effort to improve the quality of war materials.

Dr. Deming told the group that if they would follow his directions, they could achieve the desired outcome in five years. Few of the leaders believed him. But they were ashamed to say so and would be embarrassed if they failed to follow his suggestions.

As Dr. Deming told it, “They surprised me and did it in four years.”

He was invited to Japan at the end of World War II by Japanese industrial leaders and engineers. They asked Dr. Deming how long it would take to shift the perception of the world from the existing paradigm that Japan produced cheap, shoddy imitations to one of producing innovative quality products. [source]

Categories: infos Tags: , ,