1. Chapter 37 Presentation of Data 2

2. Learning Objectives Read from a time-series graph Read from a time-series graph Draw a time-series graph Draw a time-series graph Calculate moving averages Calculate moving averages Draw a moving average graph Draw a moving average graph Draw a trend line Draw a trend line Read from a trend line Read from a trend line Read from a histogram Read from a histogram Draw a histogram Draw a histogram Draw a frequency polygon Draw a frequency polygon Recognise misleading graphs Recognise misleading graphs

3. Time-Series Time always goes along the bottom Time always goes along the bottomExample The temperature of a patient taken every half hour is: Time093010001030110011301200 Temp- erature 36.937.137.637.236.537

4. Moving Averages Gives an idea of the trend taking out seasonal variations Gives an idea of the trend taking out seasonal variationsExample Calculate the moving averages in the following gas units used by a family Gas Used YearQuarterUnits 199819992000123412341234345493018827737462603194550232

5. Moving Average Graph The moving average must be plotted at the centre of the group The moving average must be plotted at the centre of the group The trend line is a line of best fit through these points The trend line is a line of best fit through these points

6. Moving Averages Graph for Gas Units Quarter 1 2 3 4 1 2 3 4 1 2 3 4 1998 1999 2000 Amount of Gas Used (Units)

7. Frequency Diagrams Bar Chart – no groups – gaps - discrete Bar Chart – no groups – gaps - discrete Bar Chart – groups – no gaps – histogram - continuous Bar Chart – groups – no gaps – histogram - continuous Frequency Polygon (Diagram)– join up the mid- points of the top of the bars Frequency Polygon (Diagram)– join up the mid- points of the top of the bars

8. Frequency Polygon This table shows the heights of some girls This table shows the heights of some girls HeightFreq 130≤h<140 140≤h<150 150≤h<160 160≤h<170 170≤h<180 351241