Charting with Excel

Getting started Click Excel2002 link Open file Extract files Open Windows Explorer Go to r:\training.dir\excelp2

Overview Why use charts Terminology Chart types Creating a chart Modifying a chart Avoiding common mistakes

Why use charts? Assist understanding of data

When to use a chart Compare item to other items (student numbers for different departments) Compare data over time (student numbers since 1980) Make relative comparisons (proportion labour, tory, lib dem, green, other) Compare data relationships (marketing expenditure/student numbers)

Terminology Data points (bars, lines, columns, sectors, points) Series (data points which come from same row or column) Value axis (y-axis) Category axis (x-axis) Legend Scale (min, max, increments) Gridlines (major & minor)

Column & Bar charts Column (vertical) Bar (horizontal) Use to compare discrete items (people, countries, days) For category data

Line charts For plotting continuous data Useful for trends over time or distance

Area chart Like a line chart, coloured in below May be stacked

XY Scatter To plot two numeric data series against each other Can add trend line

Pie For one series only Compare contribution of different components

Doughnut Like a pie chart, for two series

Specialist types Radar Bubble Surface Cylinder, cone, pyramid

Paper exercise (5 minutes) Select (and sketch) an appropriate chart type…

Chart Wizard [F11 key for instant chart] Demo dept-student-nos.xls ByDept – category column ByYear – line (category label prob) Marketing – xy Marketing – line year/nos (non adjacent) Task 1, 2, 3 – Category data Task 4 - Time series Task 5 – Numerical data

Amending existing chart Chart menu/toolbar/shortcut menu –Chart type (ByDept – change type) –Change location –Formatting –Remove series (select & delete) –Change series (right-click – Source data) –Add series (Chart > Add Data) or drag and drop Task 6– Amending evals-based chart

Adding a secondary axis Select series (demo income-profit-margin.xls) Format icon (chart toolbar) Choose Axis tab and select secondary To change data point type Select series Chart Type icon (chart toolbar)

Error bars (baby heights) Select series Double-click or right-click & Format Data Series or Format>Selected Data Series y-error bars tab –fixed values or percentages –standard deviations (plots mean and std-dev of all data – probably not what you want) –values stored in worksheet (custom option and select cells to get positive and negative errors from (if +ve and –ve errors are equal) Task 8 p. 51 Error Bars

Avoiding common mistakes Mistakes: Plotting data out of context

Mistakes: Misleading scale

Mistakes: Aspect ratio

Mistakes: Category chart for value data

Mistakes: Too many slices of pie

Mistakes: Complexity

Mistakes: Insufficient labelling Chart title Axis labels Units Legend Legibility