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Building a Model

Modelling

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It’s all in the plan

When creating a model there are a number of things that need to be thought about:

purpose of the model – what will the model do?

research – make sure you have all the information required

layout – it must be planned in a way that is simple to use

input – what information is being put in?

processing – what needs to be worked out/calculated?

output – what information will be obtained?

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Scribble it all down on paper:

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Layout: Number of students ______

Income

Money from tickets

Money from drinks

Total income___________________________

Cost

DJ and equipment

Drinks

Caretaker

Total cost______________________________

Profit (money left over)____________________

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Making the plan happen

Data Labels

Decide which spreadsheet programme to use.

Open a blank worksheet.

Enter the data labels using your plan as a guide.

Adjust the column and row width and height accordingly.

Format the data labels to improve the presentation of the model.

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Format the font to make it change colour, type, style or size.

Formatting Data Labels

Format the border to add an outside border or grid.

Format alignment to merge two cells together, align text or wrap on two lines.Format patterns to change the colour of a cell.

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Enter the formulas before entering the numeric data.

Enter the formula in the cell you want the answer.

Always start a formula with an =.

Click on the cells rather than type the cell reference to avoid mistakes.

Press enter when the formula is complete.

Adding the magic touch

Formulas

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When copying and pasting a cell, it is the formula that is copied, not the answer.

Copying formulas

The formula in cell B6 was copied into B7.

Look what happened – it changed. Why?

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When the formula was copied into B7 the computer remembered “the cell that is 4 cells away from me multiplied by the cell that is 3 cells away from me”.

That is why it copied it as =B3*B4.

It related the reference.

This is called relative cell referencing

Copying formulas

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When you want a cell reference to stay absolutely the same you need to place the $ sign in between the letter and number.

You can do this by pressing the F4 key after you select the cell B2.

Now when it is copied and pasted the cell B2 remains absolutely the same, but B3 changes as before.

This is called absolute cell referencing

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Functions are “formulas already prepared”.

Some spreadsheet software have over 250 functions ready to use.

An example is the sum function

The sum function will add any cells you want together – much quicker than the previous method of creating a formula.

Functions

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Once all the formulas have been entered it is time to add the numeric data.

As you input the numbers you will notice that the spreadsheet works out the formulas that you have placed and the answers are immediate.

Speed of calculations is one of the advantages of using a spreadsheet.

Numeric Data

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This is exactly the same as formatting data labels.

The font, alignment, border and patterns can be changed.

In addition the type of number can be changed to a variety of things including currency, date, time, percentage and fraction.

This ensures the answer is in the correct format.

Formatting formulas and numeric data

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Identify the purpose of the model.Plan the layout – it must be planned in a way that is simple to use.Draw a plan on paper to include the inputs, processing and outputs that are required of the model.Start creating the spreadsheet by entering all the data labels, followed by the formulas and then the numeric data.There are two types of cell referencing in formulas: relative and absolute.Functions are formulas that have already been programmed.All cells can be formatted.

Summary

What can I remember?