44221: Information Systems

Intro to Spreadsheets

By: Ian PerryRoom: C48E-mail: i.p.perry@hull.ac.uk

Tel: 01723 35 7287

http://itsy.co.uk/ac/0708/Sem1/44221_IS/

Ian Perry Slide 244221: Information Systems: Introduction to Spreadsheets

When to use a Spreadsheet? Whenever NUMERICAL data requires:

Calculation which may be complex, repetitive, or both.

Presentation in tabular and/or graphical format.

Analysis of complex situations.

Exploration of probable outcomes.

Ian Perry Slide 344221: Information Systems: Introduction to Spreadsheets

A ‘typical’ Spreadsheet

1

2

3

4

5

6

A B C D

R&D Cost

Rent

Travel

Personnel

TOTAL

2003 2004 2005

2360 2460 2560

800 900

8160

5000 6800

10160

Columns

Rows

Text

B6:

Cell Reference

=SUM(B3:B5)

FormulaRange

Cell Numbers

Ian Perry Slide 444221: Information Systems: Introduction to Spreadsheets

Data can be presented as a Chart

A B C D E

1 1st Qtr 2nd Qtr 3rd Qtr 4th Qtr

2 East 20.4 27.4 90 20.4

3 West 30.6 38.6 34.6 31.6

4 North 45.9 46.9 45 43.9

5

1st Qtr 2nd Qtr 3rd Qtr 4th Qtr0

1020

30

40

50

60

70

8090

East

West

North

Which may make it easier to see trends, or spot exceptional/unusual values.

Ian Perry Slide 544221: Information Systems: Introduction to Spreadsheets

The ‘simplest’ Spreadsheet Formula? Is a reference to another cell.

NB. all formulae begin with an = sign.

This is, perhaps, the MOST USEFUL spreadsheet formula; as, ideally, any data you wish to add to a spreadsheet should only be entered ONCE.

Ian Perry Slide 644221: Information Systems: Introduction to Spreadsheets

Simple Calculations i.e. using a Spreadsheet like a Calculator.

NB.

By default * and / happen before + and -

So, be careful when/if using brackets in calculations, as:

C6/D6+E6*(C6-D6)

will produce a VERY different result, i.e.:

-137.66

Ian Perry Slide 744221: Information Systems: Introduction to Spreadsheets

Simple Spreadsheet Functions - 1 Sum

=sum(range) OR =sum(cell, cell, …)

Ian Perry Slide 844221: Information Systems: Introduction to Spreadsheets

Simple Spreadsheet Functions - 2 Average

=average(range) OR =average(cell, cell, …)

Try to avoid calculating averages like this:

=(C14+D14+E14)/3

=(Sum(C14:E14))/3

as, if the number of data values in the range to be averaged changes, then you will have to remember to alter your formula.

Ian Perry Slide 944221: Information Systems: Introduction to Spreadsheets

Simple Spreadsheet Functions - 3 Standard Deviation (of population)

=stdevp(range) OR =stdevp(cell, cell, …)

Ian Perry Slide 1044221: Information Systems: Introduction to Spreadsheets

Simple Spreadsheet Functions - 4 Maximum

=max(range) OR = max(cell, cell, …) Minimum

=min(range) OR = min(cell, cell, …) Median

=median(range) OR = median(cell, cell, …) Count (of cells containing numeric data)

=count(range) OR = count(cell, cell, …) Now (i.e. today’s Date & Time)

=now() Today (i.e. just today’s Date)

=today()

Ian Perry Slide 1144221: Information Systems: Introduction to Spreadsheets

The ‘CountIf’ Function Counts the number of values in a range

that match a given criteria. =countif(range,criteria)

Ian Perry Slide 1244221: Information Systems: Introduction to Spreadsheets

The ‘IF’ Function Tests a condition in another cell, and

decides what to display in this one. =if(condition,true,false)

Ian Perry Slide 1344221: Information Systems: Introduction to Spreadsheets

Nested ‘IF’ Functions To test for more than one condition, you

could use a series of nested IF’s: =if(condition1,true,if(condition2,true,false))

Ian Perry Slide 1444221: Information Systems: Introduction to Spreadsheets

The ‘VLookUp’ Function Much easier to use than nested IF’s, when

there are many conditions to test for: =vlookup(value,range,offset)

NB. the first column of the lookup table (i.e. column E in this example) MUST contain single data values AND be in Ascending order.

Either:

ALPHABETICALLY

Or:

NUMERICALLY

Ian Perry Slide 1544221: Information Systems: Introduction to Spreadsheets

Spreadsheet Development - 1 Draft it out on paper first, considering:

Shape does the problem suit a landscape or a portrait

shaped solution? Content

which parts of the spreadsheet content will be text, data, formulae?

Outputs will the data be presented in tabular and/or

graphical format? is there a need to print the results or will they be

viewed on screen?

Ian Perry Slide 1644221: Information Systems: Introduction to Spreadsheets

Spreadsheet Development - 2 Two types of data in a spreadsheet:

Input data - entered/altered often, e.g. sales made, hours worked, money to change, etc.

Reference data - rarely changes, e.g. vat rates, pay rates, currency conversion rates,

etc.

Always separate these data types: Keep input data areas together (and easily

accessible) data entry is the biggest source of errors.

Keep reference data together and protect cells where data entry is not required.

Ian Perry Slide 1744221: Information Systems: Introduction to Spreadsheets

Spreadsheet Development – 3 Start simply:

Do not try to build a large complex spreadsheet model containing features/functions you have never used before.

Try out any new features/functions you want to use, by building a small controlled example.

Test each stage in the development of your spreadsheet model: testing each new feature/function you add;

gradually incorporating all of the functionality required.

Don't get too clever, too soon!

Ian Perry Slide 1844221: Information Systems: Introduction to Spreadsheets

Spreadsheet Development - 4 Save a "Template"

i.e. a complete spreadsheet model without input data;

containing text, formulae and reference data only. use a copy of this "Template" for testing.

Test Rigorously use data which will produce known outputs;

e.g. 1,1,1, or 50,50,50, or 100,100,100, sequences.

use someone else to test ease of data entry; you may find your design is not as easy for others.

Don't forget to amend the "Template"; if (when!) changes are required.

Ian Perry Slide 1944221: Information Systems: Introduction to Spreadsheets

This Week’s Workshop Complete this fairly simple spreadsheet model;

by adding the missing formulae.

These Lecture notes contain examples of all of the spreadsheet formulae you will need in order to complete the Workshop tasks.

You MUST only enter ‘new’ formulae in the GREEN cells, then Copy & Paste to fill in the formulae for the remainder of each Column or Row.

Ian Perry Slide 2044221: Information Systems: Introduction to Spreadsheets

The Completed Spreadsheet Model