The dashboard with the wrong total
A shop manager says: "The sales total on the screen is wrong." That is one big problem and it is hard to fix.
Is it the till? The file that carries the sales to the report? The sum in the report? The chart on the screen? A good analyst does not guess. They split the problem into parts and test each part.
By the end of this lesson
Note
I can break a data problem into smaller parts and show it in a diagram.
Key words
| Word | What it means | Example |
|---|---|---|
| Decomposition | Breaking a problem into smaller parts | |
| Feature | One main thing about a problem | the sales file |
| Characterise | Describe a feature: what it is and what it does | |
| Block diagram | Boxes that show the parts of a system | |
| Information flow diagram | A picture that shows how information moves between parts | |
| Flowchart | A picture of steps and choices, joined by arrows |
The cells students fill in are left blank in this preview.
Starter
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Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Decomposition makes a problem manageable
The purpose of decomposition is to turn one big problem into small ones. A small problem is easier to understand, test and fix.
It also lets a team share the work. One person checks the sales file. Another checks the sum.
The four tasks of decomposition
| Task | What you do | Example: wrong total |
|---|---|---|
| Identify the main features | List the big things in the problem | Till, sales file, report sum, chart |
| Characterise each feature | Say what each one is and does | The sales file carries one row per sale to the report |
| Break the problem down | Split the fault into smaller faults | Rows missing, sum wrong, chart reads the wrong column |
| Break the solution down | Split the fix into smaller jobs | Count rows, check the sum, check the chart |
The cells students fill in are left blank in this preview.
Check
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Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.