statistical analyses with openoffice.org calc

I don’t know why, but, occasionally, people may have to do minimal or even considerable statistical calculations using Calc, the OpenOffice.org‘s spreadsheet part of the Office Productivity Suite. Although, I wouldn’t recommend doing so since there are other, better software packages to complete simple and complex statistical analyses, such as R, a statistical programming language and environment with excellent analysis and graph capabilities. R can be found at one of its many mirrors.

However, for those who need or have to (or … whatever), here are some very very basic info on using statistical functions in Calc. Calc has a considerable variety of functions documented in the openoffice wiki. of statistical (and other types of) functions that you can use. There is also OOo_Stat, an external add-in, that you can include to assist you with your analyses. More on that later on.

MInd you, I am not going to provide a full “Statistics using Calc” guide here, I just want to suggest a few statistical functions for basic descriptive and inferential statistics.

A. Basic Descriptive Statistics
I. Central Tendency

  1. AVERAGE returns the mean average of its list of arguments
  2. MEDIAN returns the median value (the value at the 50th percentile) of its respective list of arguments
  3. MODE returns the most frequent value of its list of arguments

There are other functions, like GEOMEAN, HARMEAN, and TRIMMEAN which give the geometric mean, the harmonic mean and the trimmed mean (excluding a portion of highest and lowest values) of their arguments.

II. Variation

  1. KURT estimates the kurtosis of the distribution of values (ie, how flat or how tall the distribution is)
  2. SKEW estimates the asymmetry of the distribution (ie, how different from the symmetrical normal distribution it is)
  3. STDEVestimates the standard deviation of the distribution
  4. VAR estimates the variance (ie, the square of the standard deviation) of its list of arguments

Note, that there are functions STDEVP and VARPP for the standard deviation and variance of the population where the sample has come from.

B. Some (not all) inferential statistics
I. Simple tests

  1. CHITEST estimates the chisquare test of goodness-of-fit
  2. FTEST estimates the likelihood that two samples have the same variance.
  3. TTEST estimates Student’s t-test of one or two samples

II. Correlations, and simple regression

  1. CORREL estimates the Pearson product-moment correlation coefficient between two arrays of values
  2. PEARSON is identical to CORREL
  3. INTERCEPT estimates the intercept b_0 of the regression y = b0 + b1*x
  4. SLOPE estimates the slope b1 of the same regression equation
  5. STEYX estimates the residual standard error for the regression
  6. RSQ estimates the R^2, the square of the correlation coefficient between x and y>
  7. LINEST is a different kind of story. It provides a linear estimation for the data at hand. Basically it summarizes the regression analysis. It is an array function which means it must be called like this {=LINEST(arg1;arg2;arg3;arg4)}.
Linest Function Output

Linest Function Output

Data in the above example come from the R program and its cars dataset which “… give the speed of cars and the distances taken to stop” according to the help files. R help files cites Ezekiel’s 1930 Methods of Correlation Analysis published by Wiley as the source of the data and D. R. McNeil’s Interactive Data Analysis also published by Wiley in 1977) as a reference source for the data.

The output of the LINEST function consists of eight cells between F18 (upper left) and G22 (lower right) cells. Unfortunately no explanation is provided. I have tried to write in the adjacent cells some labels about each cell in the output of LINEST. Please note, that the third line of output (F21:G21) shows only the F-criterion for the fitting of data and the denominator degrees of freedom. In statistical parlance, F(1,48) = 89.57, p < 1.49e-012, which can easily be verified by using another Calc function FDIST.

There is additional output above the F18:G22 range of cells, basically the output of the CORREL, PEARSON, RSQ, INTERCEPT, SLOPE, STEYX commands from top to bottom, which all verify the output of the LINEST function.

C. OOo_STAT
An add-in macro for Calc, it comes with its own instructions on how to install it (you must enable macros) and then appears either as and additional top-level menu or as an item under Tools. OOo_STAT will not appear in Writer. It includes functions for graphics and advanced inferential statistics not available through other Calc functions. It is still in 0.5 version (which would make it a beta) but works pretty well.

After install, OOoStat gives three choices: Applications, Basic Stats, and Multivariate Statistics as shown below

OOo Stat macro

OOo Stat macro

The Applications menu allows for visualization of data via histograms and other manipulations.

OOoStat First Menu

OOoStat First Menu

The Basic Stats deals with one- and two- way ANOVA, Correlation Coefficients and Multiple Regression.

OOo_Stat Basic Stats

OOo_Stat Basic Stats

The Multivariate Analysis menu involves Principal Components Analysis, Correspondence Analysis, Multivariate Analysis of Variance (MANOVA), analyses which may be better completed using a dedicated statistical analysis package.

OOo_Stat Multivariate Statistics

OOo_Stat Multivariate Statistics

All in all, Calc provides a rather extensive set of tools (either through functions or through the OOo_Stat addin) which may assist users in their statistical analysis. However, beware, the user should always be in control of the analysis tools and not the other way round.

Enjoy,

I.

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Tips and tricks for openoffice.org

OpenOffice.
Image via Wikipedia

<Update> Soon after I hit the PUBLISH button, I received via email, the OpenOffice.org newsletter, with an extensive list of openoffice.org related blogs.</Update>

Although there is an abundance of information available at the official openoffice.org site regarding the usability and how to make openoffice.org, the free open productivity suite, work better for your needs, there are hidden treasures of information, tricks, and tips all over the place waiting to be discovered.  Here are some, in no particular order of importance or significance.

The wordpress.com site.
The trick here is to look for the tags you (or somebody else) assign to a post they publish in a wordpress.com blog.  Be as imaginative and creative as possible.  Use combinations of words.  For example, office, open, xml, lead to this page, while open, office, xml lead to this different page. Try other languages, too, and see where the hunt takes you  (if you are versed in that particular language).  For example, the same tags in german will lead you to another page, altogether.

The sun.com site
Try the sun.com site for openoffice guides and white papers.  After all, they are one of the largest contributors to openoffice.org and they still hold the license for staroffice, the suite that started all once upon a time.  Note that to retrieve white papers and guides you may have to register with a username and a valid email address.  The following two links are interesting:
Migrating from MS Office to Openoffice.org or StarOffice,
Creating large documents with Openoffice.org writer

Other blogs (of course)!!!!
Try some or all of the following (I am not affiliated with them, nor do I know their owners/editors etc.  I simply read them occasionally).
Openoffice.org engineering at sun.
Tips and training for openoffice.org.
The lifehacker page and its openoffice tips.

Finally, something that I also found while searching around:
1) Open a new spreadsheet in Calc
2) Type the following in any cell
=GAME(“StarWars”)
enjoy the openoffice version of space invaders.

For more easter eggs, … well, just look around :)

I.

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iphone update and apps to spend time

Ok, since the latest scare regarding the iphone being hijacked by a series of invisible text messages, the update to version 3.0.1 was mandatory.

iphone bios ver. 3.0.1

iphone bios ver. 3.0.1

Apparently, malicious code could be sent to the iphone via text messages, and all the rightful owner sees is a short message with a white square. More details in this detailed article.

The bios update is a bulky 240 MB download and you download it via the usual itunes channel.  It will, as usual, back up the current contents of the iphone and then go through the loops of installing and resetting the iphone. It took less than 15-20 minutes including the download time for me, but it was time well worth it.  Highly recommended for all iphone 3G and iphone 3GS owners.

Now, onto something lighter (after all, it’s august).  I have been playing a lot with these free apps for the iphone, and i like them very much. These are not the only free and fun apps residing in my iphone, but they are the ones that keep me busy all the time. Note that all links open in itunes app store:

  1. paper toss game image

    paper toss game image

    paper toss. What you get when you bring together a waste bucket, a desktop fan, and a piece of paper rolled up like a ball: Paper toss. Cleverly simple in principle, all you have to do is throw the paper in the bucket taking care of the wind coming from the fan. Wind speed and direction varies, but mission remains the same: throw the paper in the bucket.   Now, this game has some hidden treasures: try to throw the paper way off-target so that it hits the cubicle next to you and you’re gonna hear from the guy trying to work while you goof off.  The game has three levels of difficulty (easy, medium, and hard) and promises several hours of productivity of doing … nothing.  Beware, if you lose a paper toss, your streak gets erased and you go back to zero (0).
  2. wild west pinball iphone app

    wild west pinball iphone app


    wild west pinball. This is an application for the pinball afficionados with a touch of wild west flare. It includes a bank heist, a gold digg mine, a “kill-dirty-harry” shootout among other things. It has traps on each side of the controls and requires pretty good dexterity and coordination especially when the ball comes tumbling down the middle.  This is aslo a free app.  I would have liked better controls, but this is a great app all around.
  3. toobz free iphone app

    toobz free iphone app


    toobz this is the free version of the same app and offers only five levels. It is a puzzle like game and you got to build a network of interconnected water tubes just before time runs out and water is spilled. The paid apps sells for EU€0.79 and offers more levels than the free version.
  4. trains iphone app

    trains iphone app


    And finally, the one iphone app I paid to download and get addicted to it:
    trains a train dispatcher like application in which you control the switches in a yard and have to steer the incoming trains through their destinations and safely out of the yard. It features three levels: basic, advanced, and insane, and it’s got me addicted. I would have liked separate top score lists based on level but that’s ok. I got it when it retailed for only EU€0.79 but now it is sold for €1.59.

I also got an invitation to review this iLight Farts paid app, but did not get around to doing so yet.

So, there you have it.  Updated iphone and a bunch of fun apps to spend your time.

Enjoy,

I.

PS. If you like any other free (preferably) or not-so-expensive apps, please drop me a line.

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Columbine: 10 years later


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Update: A comment by a reader of the daily blah blah and a post by security expert Bruce Schneier that anyone should read. I believe that they present the same point: no matter what security measures schools take, in the end it is the school community that will solve the problem of violence./Update

Today (April 20th) marks the 10th anniversary of the Columbine High School massacre. Twelve innocent students, one teacher were killed, more than 20 were injured by two heavily armed Columbine students (before the pair shot themselves) in what became the worst school-based crime in the United States. Since then, more school-based mass killings have occured, and the BBC has an interesting (though outdated) chronology of events.

Most news outlets have carried reports and memorials for the tragic events. A partial (and incomplete) list follows:

Ten years later, the question remains unanswered: “How do you prevent such an event from happening?” In an earlier posting, I had suggested that the answer may lie in both the home and the school, both functioning/working together, side by side for the benefit and welfare of the children and the greater school community, but even this bonding may not be enough in socially turbulent times.

What do you think? Please leave a comment.

I.


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good bye to 2008 with iphone freebies


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As the year 2008 is about to depart (it has already departed in several parts of the globe), I leave you with a few free apps for the iphone, probably the coolest new gadget of the year. All of them are free apps and can be downloaded via itunes and the app store.

1. iSlots, for those who can’t live without their personal slot machine.

iSlots app

iSlots app

2. Black Jack. There is a paid and a free version, but the one we will choose is the free one.

BlackJack Free app

BlackJack Free app

3. Just to get away from the cards, the smoke and the casino atmosphere, FS5 Touch Hockey will help us do just that. One of my favorite apps for visual-motor co-ordination activities (i.e., killing time while pretending to work).

touch hockey app

touch hockey app

Happy New Year 2009.

I.


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