Maths Unit 6 – Representing Data Back to back stem & leaf diagrams are used to compare two sets of data. Stem & Leaf diagrams Comparative bar charts Ages of a group of people Types of data Pie Charts Scatter Graphs A line of best fit is drawn so that there are an equal number of points either side of the line. This can be used to predict results. Each individual piece of data is represented by a certain number of degrees. Key words and definitions Tally Chart – a method of collecting data Pictogram – a representation of data in picture form with a key to show what each picture represents Comparative bar chart – where two or more sets of data are compared using the same axes on a graph Composite bar chart – each bar displays multiple data stacked on top of one another Frequency Polygon – a graph to show the distribution of a set of data and can be used to compare multiple sets of data Correlation – is a description of the relationship between to variables. A positive correlation is when one variable increases then so does the other. A negative correlation is when one variable increases the other decreases. Pie Chart – a circle dividing into sections to show the relative proportions of a set of data