Secondary National Strategy Handling Data Graphs and charts Created by J Lageu, KS3 ICT Consultant – Coventry Based on the Framework for teaching mathematics pages

KS3 Handling Data Graphs & charts a handy guide Click on the required choice Types of data Types of graph or chart Return to last slide viewed Return to category menu

KS3 Handling Data Data types Categorical Discrete Continuous Grouped discrete Grouped continuous Means

KS3 Handling Data Categorical data is broken into categories, there is no order to the categories eg – gender - male, female – transport method – walk, bus, train etc possible graph & chart choices – pie chart pie chart – bar chart bar chart – compound bar chart compound bar chart – bar line graph bar line graph – pictogram pictogram

KS3 Handling Data Discrete data is numerical with separate values – counted eg no of letters in a word, no on a dice – ordered but not counted eg school year group, size of shoe possible graph & chart choices – pie chart pie chart – bar chart bar chart – compound bar chart compound bar chart – bar line graph bar line graph – pictogram pictogram

KS3 Handling Data Continuous data is numerical and is measured – length, weight, time etc. – even if there is rounding, say to the nearest hour, it is still continuous. We are approximating, but there is still meaning to in between points. – digital clock is continuous because it approximates. – exception - shoe size is discrete because it is labelling a type of shoe. There are only ever a certain number of shoe sizes and there is no shoe size between 3 & 3½. possible graph & chart choices – frequency diagram frequency diagram – frequency polygon frequency polygon – line graph line graph – scatter graph scatter graph – cumulative frequency diagram cumulative frequency diagram

KS3 Handling Data Grouped discrete discrete data grouped into suitable class intervals – intervals should be equal – there should be no overlap eg 0-5, 5-10 etc is wrong, where does 5 go? – unequal intervals makes the data categorical eg ages: 0-5, 6-10, 11-16, 17-21, over 21 possible graph & chart choices – bar chart bar chart – compound bar chart compound bar chart

KS3 Handling Data Grouped continuous continuous data grouped into suitable class intervals – intervals usually equal – there should be no overlap eg 0 < t < 5, 5 <= t < 10 – un-equal intervals need histograms, post KS3 possible graph & chart choices – frequency diagram frequency diagram – frequency polygon frequency polygon – line graph line graph – cumulative frequency diagram cumulative frequency diagram

KS3 Handling Data Mean mean calculated for continuous data normally over a period of time eg monthly average possible graph & chart choices – line graph line graph

KS3 Handling Data Types of graph and chart Pie chart Bar chart Compound bar chart Bar-line graph Pictogram Frequency diagram Frequency polygon Line graphs Scatter graph Cumulative frequency diagram

KS3 Handling Data Pie chart 3D distorted are not strictly correct, because the angle should be proportional to the frequency avoid unless you have a specific purpose

KS3 Handling Data Bar chart Notice the gaps between the bars Labels in the middle of the bars Main form of travel to school: pupils aged 5 to 10 two bars per category grouped data legend

KS3 Handling Data Compound bar chart Notice the gaps between the bars key labels on bars

KS3 Handling Data Bar-line graph The length of the bar represents the frequency. What is being counted or measured (the independent variable) is placed on the horizontal axis, and the count or measure (the dependent variable) on the vertical axis. It is not appropriate to join the tops of the bars.

KS3 Handling Data Pictogram all symbols should be the same size & shape fitness for purpose may justify differences, but size must be the same scale half picture=1 identical pictures mathematically incorrect

KS3 Handling Data Frequency diagram Notice there are no gaps between the bars indicating non-zero start labels start & end of bars see frequency polygon

KS3 Handling Data Frequency polygon Points are plotted at the middle of the range if grouped see frequency diagram

KS3 Handling Data Line graph data point middle month & year labels

KS3 Handling Data Scatter graph – two variables line of best fit

KS3 Handling Data Cumulative frequency diagram median