Creating Models: Spreadsheets

1
Creating Models Spreadsheets

• Letts Chapter 13

2
Introduction

• A spreadsheet program provides a table
  consisting of vertical columns and horizontal
  rows of cells. Each cell has a label called a
  reference e.g. C6, A1.
• The data placed in a cell can be
• numbers
• words and other text
• formulae to do calculations on the numbers.

3
Features of a spreadsheet

• To improve the look of a spreadsheet you can
  usually
• make columns wider or narrower
• underline and embolden data or even change fonts
• centre and justify data.
• To format of numbers can be changed including
• making them amounts of money or percentages
• changing the number of decimal places.

4
Features of a spreadsheet

• A formula is a mathematical expression which
  allows the value in one cell to be worked out
  from the value in other cells.
• A range of cells is a group of cells referred to
  as a unit. Often a range of cells is named using
  a colon (), e.g. (B3B12).
• Most spreadsheets allow functions including
  SUM, AVERAGE, COUNT, MAXIMUM and MINIMUM.

5
Features of a spreadsheet

• A powerful feature of spreadsheets is the
  ability to copy data and formulae.
• A relative reference changes when the formula is
  copied.
• An absolute reference does not change when the
  formula is copied.

6
A spreadsheet as computer model

• A spreadsheet is a simple example of a computer
  model.
• The variables of the model are cells containing
  formulae.
• The rules of the model made by the formulae.