unit 0, session 0.4 useful calculator functions j. jackson barnette, phd professor of biostatistics

Unit 0, Session 0.4Useful Calculator Functions

J. Jackson Barnette, PhD

Professor of Biostatistics

Calculator for CourseYou probably don’t need to buy a calculator for this course; you are probably carrying the best (and cheapest) calculator you can get as:

There are hundreds of apps, mostly free, that will do everything you need to do in this class and more

Unit 0, Session 0.1 Copyright 2013 JJ Barnette 2

Unit 0, Session 0.4 3

Session 0.4 Calculator FunctionsThere are many types of calculators that can

be used in this class

There are some that do many of the complex computations with a few keystrokes

I will illustrate some of these using one of my hand calculators, a CASIO fx-115MS

Keys vary by calculators so yours may be different, but should have the same operations that can be done

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SQUARE-ROOT

Finding a Square-root. The order of the key strokes is important and will vary.To find the square-root of a given number, press the square-root key, then enter the number on the keypad, and press the equal sign.

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SQUARE-ROOT

To find the square-root of a value that has been calculated using other operations, press the square-root key, then press the Answer key, and then press the equal sign. This will find the square-root of the previous answer.

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FACTORIAL

To find a factorial X!, enter the number X, press the SHIFT key, then the factorial key, then the = sign key.

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NATURAL LOG

To find the natural logarithm of a number, press the ln key, then enter the number, then the = sign key.If you want the natural log of a computed answer, press ln, then Ans, then the = sign.

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MULTIPLYING BY e

To multiply a numberby the constant e (2.71828..), press theALPHA key, then thee key, then the multiplication key (X),enter the number to be multiplied, and then press the = key.

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FINDING e TO A POWER, ex

Used to convert anatural log back to an original scaled value. Press the SHIFT key, press the ex key, enter x on the keypad (the exponent, include – sign if negative), then press = key.

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TAKING A VALUE TO A POWER, Xy

Many calculators have this key. If so,enter X, then pressthe key, then enter y(the exponent), then=.On mine, enter X on the keypad, pressthe ^ key, then enter y (the exponent), andthen press =.

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Combinations and PermutationsWhen we study the topic of probability, we will use

two types of counting procedures

One is the number of combinations of r items taken from n different possible items (see 0.2, 8),

The other is the number of unique sequences of r items taken from n possible items. These are Permutations (see 0.2, 9),

These are very time-consuming to compute from scratch, many calculators do these automatically

rnP

rnC

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Combination Key

Order: Enter n first, press key, enter r next, press = sign

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COMBINATIONS, nCr

Combinations are the number of unique combinations of r items taken from a group of n differentitems.Here’s the key (SHIFT)on my calculator that finds this.Enter n on the keypad, press the nCr key, enter r and then the = key.

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COMBINATIONS, nCr

Combinations are the number of unique combinations of r items taken from a group of n differentitems.Here’s the key (SHIFT)on my calculator that finds this.Enter n on the keypad, press the nCr key, enter r and then the = key.

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Permutation Key

Order: Enter n first, press key, enter r next, press = sign

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PERMUTATION, nPr

Permutations are the number of unique sequences of r items taken from a groupof n items.Here’s the key (SHIFT)on my calculator that finds this.Enter n on the keypad, press the nPr key, enter r and then the = key.

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PERMUTATION, nPr

Permutations are the number of unique sequences of r items taken from a groupof n items.Here’s the key (SHIFT)on my calculator that finds this.Enter n on the keypad, press the nPr key, enter r and then the = key.

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Conclusion

This is the final session in Unit 0

It is intended as a review of basic mathematics used in biostatistics with a focus on how these will be used in this course

If there are mistakes found of other topics that you feel should be included, please contact Dr. Barnette

Unit 0, Session 0.4