4. Spreadsheet Concepts

Objects - Buildings, cars, roller coasters and weather

Mathematical- calculations , financial forecasting

Object Modelling:

• Computers can create virtual representations of an object within a computer e.g. buildings, floodings and earthquakes
• Different scenarios can be then examines to forecast what may happen in a given event e.g. building collapse
• These mdoels can also be speeded up e.g. to demonstrate the effect of floodings in areas of rising seawater
• Scientist can use these models to predict what ares may be affected and to what extent
• It is safer to make a tried and tested prototype that has been tested on a computer than testing it out in real life
• E.g. New aircraft - if it will not fly properly in a model then no one will get hurt testing it
• New tyres - can be tested for blowouts this is much safer than driving a car and waiting for the tyre to blow out
• New buildings - can be tested for storm conditions and how well they can withstand earthquake damage

Advantages:

• What if questions can be asked without having to build a model from scratch each time a test is run
• Automatic recalculation: If a change is made then all related formulae and values will change 
• Graphs can be produced: these will automatically change as any values change 
• Variables and constants can be used this enables the entire model to be changed by changing one or more values
• The model can be saved and backed up: if the the original is lost or corrupted there is a copy 
• The model can be shared between different people in different locations 
• No additional software is required: spreadsheets are standard business software. Most people  are able top use a spreadsheet, so no specialist training is needed.
• It might be quicker and cheaper to build a computer model than a physical one
• Only one model needs to be built, which then can be changed. If a physical model is built then a different one will have to be built each time a change is made

• It can be safer to run a stimulation/model under extreme conditions than to build an actual model and test it.
• For example, testing a ship in storm conditions
• Computer based models can be speeder up or slow down to see effects that are diffult to see in real life

• The model may not be an accurate representation of the real world 
• If the model relates to people then an accurate result may not be given 
• Many variables need to be considered and it is easy to miss things out this may lead to misleading errors 
• Providing an effective !model may be time consuming and running the model may need expensive hardware and software 

Spreadsheets are also used a lot for financial and mathematical calculations. The cpts of times can be shown and individual cells can have different values

Variables, Formulae, Rules and Functions are the four main characteristics of spread sheet software

Variables: This is an identifier associated with any particular cell. The variable can be a cell reference e.g. A2 or a cell name e.g. CALCULATE_TOTAL

Formulas: These are a way a spreadsheet can perform calculations. They use numbers, cell references and the mathematical operators +/×÷ e.g. A1 + (A2 × TOTAL)

Rules: A rule is a procedure that must be followed. Validation can be applied to a rule to ensure the calculation is done correctly. For a calculation to work a sequence of events have to take place. 

Functions: These are used to present any formula that is too difficult to remember. A function uses preset words that are built into the spreadsheet e.g. SUM, MIN, MAX, AVERAGE AND LOOK UP 

Cell: known by its cell reference e.g. A2

Cell Reference: A group of cells known as a range and identified by the top left cell reference to the bottom right cell reference e.g. B4:D7

Worksheet: A large grid of cells within a worksheet. A worksheet can hold data for an organisation 

Workbook: A workbook is made up of a collection of worksheets. A workbook in an organisation could be made up of 4 different worksheets 

Rows: Go accross a spreadsheet 

Column: A column of cells that go down a spreadsheet 

• This is when it mopves in relation to the direction in which it is being copied 
• With this the spreadsheet formula changes to be relative to that column or row 

• This is when it stays on the same place 
• This iOS when the referenced cell in a formula remains exactly the same when the formula is copied to other cells 
• E.g. The vat rate, whenever this value VAT is referenced in a formula it will always be the same 
• Absolute referencing is good for fluctuating costs like postage cots or VAT rate 
• $ sign is put before the column and row part of a cell reference