Bivariate Oddities This aplet contains sets of bivariate data which have the same summary statistics but totally different 'shapes' when graphed. They illustrate the need to rely on more than just the stats when deciding on whether a linear model is appropriate! More Information Author: Colin Croft
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Coin Toss
Highly recommended.  This aplet investigates the common charity game consisting of tossing of a coin onto a square grid.  It requires only knowledge of quadratic functions and can be used at a number of levels:
 to illustrate the convergence of experimental values towards theoretical ones. to investigate fitting a quadratic curve to experimental data. to introduce the idea of a probability function.
Note: I have recently revised this aplet, making it considerably faster and adding the ability to exit and restart with retention of existing data.
More Information

Author: Colin Croft

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 Central Limits Theorem One of the most fundamental theorems in the study of statistical inference is the Central Limits Theorem. This states basically that the means of successive random samples taken from a population will be normally distributed whatever the underlying parent distribution. This aplet illustrates this and that the standard deviations are related by ratio. Sampling can be done from different parent distributions and the resulting collection of means compared to the equivalent Normal distribution. It is fairly slow to execute because of the need for repeated sampling but would be quite useful to teachers.
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 Correlation This small but handy aplet created by David Kranz allows you to find the correlation and line of best fit from summary statistics. Only the 39/40G version is available and this is not likely to change.
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 Dandelions This aplet uses visual methods to illustrate and introduce the Poisson distribution, through the sowing of dandelion seeds into a large patch of ground, which is then broken up into unit squares. More Information Author: Colin Croft
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 First 50, The This is a collection of small programs you can type in yourself or download.  They perform a multitude of small tasks, some that are so easy you'll wonder why I wrote a program for them, some that are really cool. For FAR more information click here. Author: Colin Croft
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 Fisher Z Transform Using the Fisher Z Transform aplet, the student will be able to perform standard calculations involving Hypothesis Test and Confidence Interval about ρ (correlation coefficient). Author: F. Frascati
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 Grouped Data This aplet calculates and displays measures of central tendency and spread for data which has been grouped into intervals. The user puts the interval mid-points into C1, the frequencies into C2 and the aplet will display the mean, proportional median, lower and upper quartiles and various other values. The user can also perform calculations such as finding the values which cut off the top 15% of data, the middle 30% etc. Update (9May'04): Fixed a small bug in the graph display. Author: Colin Croft
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Inference
This aplet gives inferential statistics access for the 38G similarly to that of the 39/40G, covering both Hypothesis Testing and Confidence Intervals.  The interface is not as smooth as the 39G version and there is no graphical view to aid in your judgement but it does the trick extremely well and fills a hole in the capabilities of the 38G.  Documentation is included. Many thanks to Detlef Muller for transforming it from my HPBasic program that used 75% of memory on the calculator to an assembly code aplet that uses only 23%!
Note: See also Statpack 39/40.
###### Updated (7/1/05): Fixed a small bug that gave an error in one of the calculations. Spotted by Fabio Frascati. Thanks to Detlef for revisiting the code so long after he wrote it.

Author: Colin Croft, Detlef Mueller.  For source code click here.

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 Key Finder This aplet uses a statistical model to simulate a person trying to find one particular key of six in their pocket. A investigation into the average run length when throwing dice. More Information Author: Colin Croft
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KeyDebounce
The internal keybounce time is set in order to prevent a key registering twice.  When you press a key you may only hold it down for a fraction of a second but to the calculator this is a LONG time and if there were no delay set then it might, for example, read what you meant to be a '3' as a '33'.  However the default factory setting of 166.6ms delay is a little high and sometimes causes a REAL press of '33' to only register as a single '3' when you actually meant 33!  Changing the delay value to a setting of around 75ms will reduce the chance of this happening.

When you first run the aplet it will display the current delay time.  For an HP39G this is 166.6 milliseconds.  You can alter this to any value from 0 to 400.  Based on my experience a good value to try is somewhere around 100ms.

Once the value is set it will remain until a memory reset (ON+SK3 or ON+SK1+SK6) is performed on the calculator. Deleting the aplet will not affect it and, since the aplet is only 1.3Kb in size, it may be worth retaining.

###### Note: This aplet was written for the old 39G/40G that have since been superseded by the 39gs/40gs. It makes calls directly to the chip and may not work for the 39gs. It may have no effect or it may even lock up the calculator, requiring a reset!. I've not tested it. Feedback would be appreciated.

Author: Detlef Mueller

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 Linear Fit The student nominates what they think is the line of best fit for a set of bivariate data. They can then adjust the line interactively, seeing the effect on the sum of squares of residuals.  The HP38G version is an effective teaching tool even if a bit slow but new commands available on the HP39G have let me speed that version up considerably. More Information Author: Colin Croft
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 Maths & Chem Library This aplet allows the 39g to execute a number of new commands for use in the Western Australian TEE subjects Calculus, Chemistry and Applicable Maths. It contains a number of small routines for use in exams. To use the commands, simply type the desired command in the home screen as you would an inbuilt command. Most of them can also be done using the Solve aplet but this is faster. ====COMMANDS==== * BIN(x,n,p) - finds the binomial probability of X=x * CBIN(x,n,p) - finds the binomial probability of a=X=b * POI(x,µ) - finds the Poisson probability of X=x * CPOI(a,b,µ) - finds the Poisson probability of a=X=b * EXPON(a,b,µ) - finds the exponential probability of a=X=b * CIS(n) - performs the complex operation CIS on any angle To find the atomic mass of any element, type the atomic formula (eg He for helium) followed by a full stop, and press enter. Author: Alan Lark
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 Probability Distributions (Updated!) An essential tool for any student going into an exam which involves probability functions. This is two copies of the Solve aplet with equations pre-entered for Discrete and Continuous probability density functions respectively. Covers the Binomial distribution (individual & cumulative), the Poisson distribution (individual & cumulative), the Exponential function, the Normal distribution, plus more.  Make sure you read the documentation. Note: Updated 19/4/03 to split it into Discrete and Continous PDFs.          Prior to that all equations were in one aplet. Updated 30/8/04 to fix an error in the documentation. Updated 11/9/05 to fix another error in the documentation. Author: Colin Croft, Craig Davis & various students.
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 Probability Inverse This is an aplet created by Fabio Frascati. It is quite similar to the Probability Distributions aplet above except that it deals with more advanced probability functions and that it has been automated via the VIEWS menu. Well worth downloading for any student using this level of statistics. Author: Fabio Frascati.
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 Serpinski This aplet illustrates the chaotic production of Serpinski's Triangle by random processes which nevertheless produce a deterministic result. Author: Detlef Mueller
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 Simulations This aplet allows the teacher to simulate sets of observations on a multitude of discrete and continuous probability distributions for use in tests and exams. It will probably not be of interest to students. More Information Note: Updated (9/12/00). The zip file was not extracting properly.  No change to the aplet itself. Note: Updated (27/8/04). Added the ability to simulate the Poisson distribution. Author: Colin Croft
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 Statpack39/40 This is an incredibly useful package for advanced stats developed by Tim Wessman in the US.  It massively enhances the statistical capabilities of the HP39G or the HP40G with a number of new functions. An absolute must for any university mathematics students.  An HP38G version is not available and is not likely to be.   Click here to view the documentation in PDF format, or click on the link on the right to download the whole package (118Kb). Note:  The author is currently out of touch and will not be available until 2004.  Any bugs or problems should be reported to me and I will pass them on later.  I have the source code if any machine code programmer is interested in doing maintenance. You'd need experience in using sRPL on the HP48 or HP49. Author: Tim Wessman
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 Time Series This aplet performs time series analysis using any length moving averages from 2 to 8 points. It includes extensive graphing facilities and the ability to produce seasonally adjusted data. More Information Note: Updated 25/3/05 so that it does more than just 3,4 or 5 point moving averages. Author: Colin Croft