Basic Statistics Lecture five and six Graphical Representation

Basic Statistics Lecture five and six Graphical Representation of Data

Bar Graph 35 30 25 20 Series 1 15 10 5 0 90 -100 80 -89 70 -79 60 - 69 50 -59 40 -49 30 -39 20 - 29 10 to 19 0 -9 A bar graph is a graph that uses separated bars to represent frequencies. Bar graphs are used to organise and present data that ate categorical. The bar do not touch each other.

Histogram A histogram is a graph that uses bars to represent frequencies; the bars touch.

Line Graph 140 000 120 000 100 000 80 000 under 18 18 -24 25 -39 60 000 40+ 40 000 20 000 0 1999 2000 2001 2002 2003 2004 2005 Line graphs are used to show trends in data at equal intervals. 2006

Pie Chart 90 -100 80 -89 70 -79 60 - 69 50 -59 40 -49 30 -39 20 - 29 10 to 19 0 -9 A pie chart is a graphic representation of the proportion ( or percentage ) of each category set of data. They have great visual impact and are commonly used in newspapers and magazines.

Stem and Leaf Diagram • Stem and leaf retains data in its original form by providing a visual representation. • For example, let us construct a stem and leaf diagram for the following Reading scores. • 80, 85, 110, 95, 100, 45, 95, 130, 75, 80, 100, 120, 110, 125, 75, 100, 40, 75, 110, 150

steps • Split the data into two pieces the stem and leaf • Arrange the stems from low to high • The leaves on the right should be in order of magnitude. • No commas should appear on the right • There should be at least five but no more than twenty rows.

To Recap the data presented are as follows: 80, 85, 110, 95, 100, 45, 95, 130, 75, 80, 100, 120, 110, 125, 75, 100, 40, 75, 110, 150 Stem and Leaf Diagram • • • 4 5 6 7 8 9 10 11 12 13 14 15 05 05555 0005 5555 000 05 0 0

Graphing In graphs, the axis of the variables are assigned, then scales and labels are added. | The dependent variable | • is always assigned to the y-axis. | • relies on the changes in the independent | variable (reaction). | • is what we measure. | |________________ The independent variable • is always assigned to the x-axis • does not rely on an other variable (action). • values can be chosen freely.