Data+Handling

Two way tables
Two way tables are used in your everyday life, you use them everytime you check your school timetable for you lessons. These tables can hold information that is easy to access. What I want you to start thinking about now is instead of just being able to read a two way table, what does the information tell you?

The number of hours t that students watch tv for on a weekday.
 * || 0 3 || Total ||
 * Boys || 3 || 3 || 9 || 5 || 20 ||
 * Girls || 7 || 5 || 5 || 3 || 20 ||
 * Total || 10 || 8 || 14 || 8 || 40 ||

What does this data tell us about the amount of time boys spend watchingg tv in an evening compared to the boys? Can we say that boys watch more tv than girls? What other statements can you say about this data?

Measures of location - Averages
The **Mode** is the most frequent. In a list of data it will be the number or thing that appears most often. In a frequency table it will be the number or thing with the highest frequency. The **Median** is the middle number when the data is order from smallest to largest. The median will be placed at the 1/2(n+1) th value where n is the number of data. In a frequency table, remember that the data has already been ordered for you. The **Mean** is the total frequency divided by the number of data.





Histograms
A histogram is different to a bar chart in that the AREA is the frequency rather than the height. The class widths (grouped data on x axis) are not always equal. A histogram represents continuous data so there will be no gaps between bars. The y axis will be labelled frequency density rather than frequency.




 * __Frequency__ = Frequency**
 * Class width**


 * Frequency = class width x frequency density**

__Example of a Frequency Table used for a Histogram__


 * || 110<h<115 || 115<h<120 || 120<h<125 || 125<h<135 || 135<h<145 || 145<h<150 || 150<h<170 ||
 * Frequency Density || 0.6 || 1.4 || 2.6 || 2.9 || 2.1 || 1 || 0.3 ||
 * Frequency || 3 || 7 || 13 || 29 || 21 || 5 || 6 ||
 * Class Width || 5 || 5 || 5 || 10 || 10 || 5 || 20 ||