Microsoft ® Office Excel ® 2003 Training Statistical functions in Excel CGI presents:

Microsoft® Office Excel® 2003 Training

Statistical functions in Excel

CGI presents:


Course contents

• Overview: Using statistical functions, formulas

• Lesson 1: Excel and statistics—The basics

• Lesson 2: Write good formulas

• Lesson 3: Which function to use?

Each lesson includes a list of suggested tasks and a set of test questions.


Overview: Using statistical functions, formulas

Learn about using statistical functions and formulas in Microsoft Office Excel 2003, from the very basics to choosing the right function for you.Learn also how to troubleshoot common problems.


Course goals

• Use a statistical function in an Excel spreadsheet.

• Assess which statistical function to use in a particular situation.

• Avoid some common errors when using functions.

• Understand why some statistical formula results are more accurate in Excel 2003 than in previous versions.

Lesson 1

Excel and statistics: The basics



Building a formula in Excel using statistical functions is no more difficult than using any other function.

You just have to know how to use Excel functions and know a bit about statistics.

Use Excel to manage your statistical data.



Using Excel to do everyday statistical calculations can save you a lot of time and effort.

Use Excel to manage your statistical data.

This lesson will explain the basics of why you might want to use Excel, and gives a quick reminder on how to build formulas in Excel.


Why Excel?

There are many practical applications of statistics in Excel:

Excel statistical functions have many uses.

• A sales manager might want to project the next quarter's sales (TREND function)

• A teacher might want to grade on a curve based on average scores (AVERAGE, MEDIAN, or even MODE functions)


Why Excel?

• A manufacturer checking product quality might be interested in the range of items that fall out of acceptable quality limits (STDEV or VAR functions)

Excel statistical functions have many uses.

• A market researcher might need to find out how many responses in a survey fell within a range of responses (FREQUENCY function)


Variance in action

Imagine a sales manager looking at the sales figures for three different salespeople to compare their performances.

One of the many statistical functions the manager could use is variance (VAR).


Variance in action

• Variance measures how different the individual values of the data are from one another.

• Data with low variance contains values that are identical or similar, such as 6, 7, 6, 6, 7.

• Data with high variance contains values that are not similar, such as 598, 1, 134, 5, 92.


How to construct a statistical formula

If you know how to use a function in Excel, you can use a statistics function.

They are written in the same way:

1. Always start with an equal sign (=).

2. Then the function name.

3. Then the arguments in parentheses.Finding the variance based on a range


When Excel isn't enough

If you're doing heavy-duty statistical analysis, Excel might not be powerful enough for your needs.

An example is doing research in a lab. If you do regression analysis, Excel requires that the x values be in a single block (adjacent rows or columns), which might not be convenient for you.



In these circumstances, you might want to use a dedicated statistical package because it covers a larger set of statistical analysis options and related functions.

Some packages also display additional outputs associated with a particular analysis.



Many of these statistical analysis programs are commercially available.

• There are also specially designed add-ins for Excel from other companies.

• Some of them can be found in the Office Marketplace on Microsoft Office Online.


Suggestions for practice

1. Calculate variance by typing cell references.

2. Calculate variance by clicking the cell references.

3. Calculate variance by dragging across a cell range.

4. Interpret the results.

Online practice (requires Excel 2003)

http://office.microsoft.com/training/training.aspx?AssetID=RP010919301033&CTT=6&Origin=RP010919291033


Test 1, question 1

To use statistical functions with Excel, you must have: (Pick one answer.)

1. A statistical add-in package.

2. You can't do statistics in Excel.

3. A computer with Excel installed.

4. A degree in statistics.


Test 1, question 1: Answer

A computer with Excel installed.

All you need is Excel; it has many statistical functions built in.


Test 1, question 2

How do you create a statistical formula in Excel? (Pick one answer.)

1. It's exactly like any other formula: type the equal sign (=) and then the function name followed by the data information.

2. On the Data menu, click Statistics.

3. On the Insert menu, click Statistics Function.



It's exactly like any other formula: type the equal sign (=) and then the function name followed by the data information.

Statistical formulas are no more complicated than any other formula.


Test 1, question 3

Which of these is a formula in Excel? (Pick one answer.)

1. STDEV

2. =STDEV(A1:A33)

3. NaCl



=STDEV(A1:A33)

A formula in Excel includes an equal sign, a function name, and the arguments in parentheses.

Lesson 2

Write good formulas


Write good formulas

If Excel is so great for doing statistics, why doesn't everyone use it?

Success with Excel requires good formulas.

• Sometimes it's hard to know what Excel can do.

• People can get errors when trying to get the results they want.


What's the problem?

To build better formulas in Excel:

• Increase your knowledge of functions

• Avoid the common mistakes that many people make

Incorrectly written formulas return error messages.


What's the problem?

Anyone using Excel — not just those using statistical functions — encounters these problems.

The main thing is to use the right function and to know how to write a proper formula.

Using an incorrectly written formula — or the wrong function — usually results in an incorrect answer.

Incorrectly written formulas return error messages.


How to solve the problem

There are plenty of sources of information to help you out.

You can learn to write better formulas with such resources as:

The Insert Function dialog box

• This training course

• Excel Help topics

• The Insert Function dialog box



In the Insert Function dialog box, you can:

• Choose which type of function you're looking for

• Select a specific function from a list of functions

• Get a description of that function as well as request help on it




To open the Insert Function dialog box, click Function on the Insert menu. Then:1. Pick the function type you need.

2. Find the function name in the list.

3. Check the function description to make sure you've selected the right one.

4. Click the Help link if you need more information.




Note If you can't find the function you're looking for in a particular category, try a related category. For example:

• AVERAGE, the function for arithmetic mean, is listed under the Statistical category, not in Math & Trig, as you might expect.

• RAND, the random number function, is listed under Math & Trig.



The importance of spelling

Now take a look at the Normal Distribution, which is a smooth, symmetrical, bell-shaped curve.

If you measured the height of a sample of plants grown under the same conditions, the distribution of the heights would approximate the Normal curve.

The area under the curve up to z shows the prob-ability of getting z. These values are also available in statistics tables.



There are two functions in Excel for the Normal Distribution:

• NORMDIST

• NORMSDIST




In the practice session you'll use the NORMSDIST function, which calculates probabilities associated with the Standard Normal Distribution. The Standard Normal Distribution curve is centered at 0 (the mean).



More common problems

Some of the most common mistakes when building formulas include:

• Forgetting the equal sign (=) at the start of the formula.

• Inserting a space before the equal sign.

• Having your data in the wrong format (for example, as text rather than as numbers).

• Selecting the wrong data range.

Some common errors in spreadsheets


More common problems

If you have something wrong in a formula, Excel might return an incorrect result, such as #VALUE!, as shown in the illustration on the left.

Some common errors in spreadsheets

These problems can be easily avoided. A full list of error types and ways to solve them is available in the Help topics.



1. Troubleshoot some common problems.

2. Use the Insert Function dialog box.

3. Write a formula.

4. Analyze the results.


http://office.microsoft.com/training/training.aspx?AssetID=RP010919381033&CTT=6&Origin=RP010919371033


Test 2, question 1

What character should you use at the start of every function? (Pick one answer.)

1. +

2. #

3. (

4. =



=

Every formula must start with an equal sign.


Test 2, question 2

Which of these is a valid formula in Excel? (Pick one answer.)

1. NORMSDIST(0.3)

2. =NORMSDIST (0.3)

3. =NORMSDIST(0.3)

4. =NORMSIDST(0.3)



=NORMSDIST(0.3)

This is a perfectly valid formula.


Test 2, question 3

How do you display the Insert Function dialog box? (Pick one answer.)

1. On the Insert menu, click Function.

2. On the Function menu, click Insert.

3. On the Tools menu, click Insert Function.



On the Insert menu, click Function.

Lesson 3

Which function to use?


Which function to use?

You've mastered writing formulas in Excel. You know to start with the equal sign and how to troubleshoot some error messages.

What else could possibly cause a problem? Could you still get incorrect results?


Still have the wrong answer?

If you're not sure which function to use, there's only so much help that Excel can give you. You need to be able to analyze your data: even when you think you know which statistical function you want, some statistical knowledge is necessary.



Still have the wrong answer?

Many similarly named functions in Excel are related to one another.

If you've picked a function that does something slightly different from what you intended, make sure you've got the right one.

• Check the purpose of each individual function in the Insert Function dialog box and use the link to the Help topics.



Which function?

Another example of a statistical function that has more than one option to choose from in Excel is standard deviation.

A sample population and an entire population


Which function?

The standard-deviation functions available in Excel are:

A sample population and an entire population

• STDEV

• STDEVA

• STDEVP

• STDEVPA


Which function?

STDEVP and STDEVPA both use entire populations, whereas STDEV and STDEVA work on samples of populations. This is a statistical difference.

Function Type of statistical data

Type of Excel data

STDEV Sample Numeric

STDEVA Sample Numeric, logical, and text

STDEVP Population Numeric

STDEVPA Population Numeric, logical, and text


Which function?

STDEVA and STDEVPA will recognize TRUE and FALSE text (or logical values) as well as numerals.

STDEV and STDEVP will only recognize numeric values.

Function Type of statistical data

Type of Excel data

STDEV Sample Numeric

STDEVA Sample Numeric, logical, and text

STDEVP Population Numeric

STDEVPA Population Numeric, logical, and text


Better results in Excel 2003

Some functions will give different results in Excel 2003 compared to previous versions of Excel:

• Various functions were improved “behind the scenes.”

• Excel 2003 uses a “two–pass” procedure, which increases the accuracy of the results.

Excel 2003 is more accurate than Excel 2002.



1. Work with functions that accept logical values.

2. Compare values between entire population functions and sample population functions.


http://office.microsoft.com/training/Training.aspx?AssetID=RP010919451033&CTT=6&Origin=RC010919231033


Test 3, question 1

You have worked out a function in Excel, but double-checking on a calculator gives a completely different result. What should you do? (Pick one answer.)

1. Check that you've used the right Excel function.

2. Panic.

3. Find another calculator.

4. Assume Excel is correct.



Check that you've used the right Excel function.

You can easily get different results by using similar, related functions. The first thing to do is check that you have the right function. It's also possible that Excel and a calculator will yield slightly different results if you're looking at a large number of significant figures.


Test 3, question 2

If you're not sure about which function to use, what should you do? (Pick one answer.)1. Consult a statistics text book.

2. Try them all and see what looks right.

3. Check the Insert Function dialog box.



Check the Insert Function dialog box.

Use either the description in the Insert Function dialog box or the link to the Help topics to get information about what each function does.


Test 3, question 3

You have a worksheet created in Excel 2002. When you update the worksheet in Excel 2003, some of the results change. Which result set is the most accurate? (Pick one answer.)

1. Excel 2003.

2. Excel 2002.



Excel 2003.

Some functions were updated in Excel 2003 to give more accurate results.


Quick Reference Card

For a summary of the tasks covered in this course, view the Quick Reference Card.

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Documents

Microsoft ® Office Excel ® 2003 Training Statistical functions in Excel CGI presents: