40 Number of Parking Tickets Monday Tuesday Wednesday Thursday Friday Pictograms and Bar Charts Friday Thursday Wednesday Tuesday Monday Line Graphs

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Diagrams are often used to show information from data. e.g. The following data set shows the number of cars given parking tickets on a particular street on 5 weekdays. MondayTuesdayWednesdayThursdayFriday As always, the frequencies are numbers, but we don’t have numbers for the days of the week. The data are qualitative (descriptions) instead of quantitative (quantities or numbers). Both types of data can be shown in pictograms and bar charts.

MondayTuesdayWednesdayThursdayFriday e.g. A pictogram of the data. Friday Thursday Wednesday Tuesday Monday Decide how many real cars are represented by a picture of a car. Ans: 10 Key: = 10 cars The diagram must have a title and key. pictogram  picture Number of Parking Tickets 20

There is very little difference between a pictogram and a bar chart. We replace the pictures with bars ! Friday Thursday Wednesday Tuesday Monday Number of Parking Tickets As before, we must have a title but instead of a key we have a scale. Bar charts are easier to draw using squared paper

Number of Parking Tickets Monday Tuesday Wednesday Thursday Friday Thursday Wednesday Tuesday Monday Number of Parking Tickets Bar charts are often drawn with the bars going up the page. Friday Thursday Wednesday Tuesday Monday Number of Parking Tickets Number of Parking Tickets Friday Thursday Wednesday Tuesday Monday Friday Thursday Wednesday Tuesday Monday Number of Parking Tickets To find the mean number of tickets issued per day, we sum the frequencies and divide by the number of days.

40 Number of Parking Tickets Monday Tuesday Wednesday Thursday Friday Thursday Wednesday Tuesday Monday Number of Parking Tickets Bar charts are often drawn with the bars going up the page. Friday Thursday Wednesday Tuesday Monday Number of Parking Tickets mean number of tickets issued per day = = 24

Double, or dual, bar charts can be used to compare data. This chart compares the way that boys and girls in a junior class travelled to school. Frequency Bus Train Taxi Walking Methods of Transport to School Frequency Boys Girls Answer the following: (a)How many girls go by train? (b)How many children go by taxi? (c)What is the most popular way of getting to school? Ans: (a) 2 (b) 4 (c)Walking

A line graph is mostly used when data are given at regular intervals of time. For example, times of day, months, or years. Year Number (millions) e.g.The table shows the total number of recorded crimes in England and Wales. Source: Office for National Statistics: British Crime Survey, Home Office Draw a line graph to display the data. Solution: We plot the years on the x -axis (horizontally) and the number of crimes up the y -axis (vertically). The points are joined with straight line segments.

Year Number (millions) Total Number of Crimes committed in England and Wales Year Solution: Tell your partner 2 things the graph tells you about the number of crimes. x x x x x x Between 1991 and 2001, most crimes occurred in Crime decreased each year from 1995 to ( Other answers are possible. ) Number (millions)

Exercise 1.The diagram shows the spending by overseas tourists in parts of the U.K. in SW England Heart of England Wales Scotland Area Source: Office for National Statistics Key: = £ 100 million (a)How much was spent by the tourists in (i) the Heart of England and (ii) Wales? (b)The figure for SW England was £ How many pictures would show this?

Area Scotland Wales Heart of England SW England Exercise Source: Office for National Statistics Key: = £ 100 million (a)(i) £ 700 million was spent in the Heart of England (ii) £ 250 million was spent in Wales. Answers: (b) 4½ pictures are needed to show £

2.The diagram shows the estimates of fish stock in the North Sea in the 1970 s and 1990 s. (a) Which type of fish stock increased between the 1970 s and the 1990 s? (b)What was the estimate of the stock of cod in the 1970 s? Ans: Ans: ( 800 thousand ) tonnes North Sea Fish Stocks Cod Herring Haddock Frequency ( thousands of tonnes ) 70's 90's Source: Office for National Statistics Herring

 Qualitative data has descriptions instead of numbers. SUMMARY  Pictograms and bar charts can be used to display qualitative and quantitative data. e.g.days of the week, colours, transport methods.  Pictograms must have a title and a key. The key gives the frequency for each picture.  The lengths of the bars on a bar chart give the frequencies. Bar charts must have a title and a scale.  Line graphs have straight line segments joining the points. The x -axis often shows time.

A histogram is a bar graph that shows the frequency of data within equal intervals. There is no space between the bars in a histogram. Course 2 Histograms

The table below shows the number of hours students watch TV in one week. Make a histogram of the data. Additional Example 3: Making a Histogram Step 1: Make a frequency table of the data. Be sure to use equal intervals. Course 2 Histograms 6 /// 7 //// //// 8 /// 9 //// 1 // 2 //// 3 //// //// 4 //// / 5 //// /// Number of Hours of TV 1–3 Frequency Number of Hours of TV 15 4–6 17 7–9 17

Additional Example 3 Continued Step 2: Choose an appropriate scale and interval for the vertical axis. The greatest value on the scale should be at least as great as the greatest frequency. Course 2 Histograms 1–3 Frequency Number of Hours of TV 15 4–6 17 7–

Additional Example 3 Continued Step 3: Draw a bar graph for each interval. The height of the bar is the frequency for that interval. Bars must touch but not overlap. Course 2 Histograms 1–3 Frequency Number of Hours of TV 15 4–6 17 7–

Additional Example 3 Continued Step 4: Label the axes and give the graph a title. Course 2 Histograms 1–3 Frequency Number of Hours of TV 15 4–6 17 7– –3 4–6 7–9 Hours of Television Watched Frequency Hours

The table below shows the number of hats a group of students own. Make a histogram of the data. Try This: Example 3 Step 1: Make a frequency table of the data. Be sure to use equal intervals. Course 2 Histograms 1–3 Frequency Number of Hats Owned 12 4–6 18 7– // 2 //// 3 //// / 4 //// / 5 //// /// 6 //// 7 //// / 8 //// //// 9 //// //// Number of Hats Owned Frequency

Try This: Example 3 Step 2: Choose an appropriate scale and interval for the vertical axis. The greatest value on the scale should be at least as great as the greatest frequency. Course 2 Histograms 1–3 Frequency Number of Hats Owned 12 4–6 18 7–

Try This: Example 3 Step 3: Draw a bar graph for each interval. The height of the bar is the frequency for that interval. Bars must touch but not overlap. Course 2 Histograms 1–3 Frequency Number of Hats Owned 12 4–6 18 7–

Try This: Example 3 Step 4: Label the axes and give the graph a title. Course 2 Histograms 1–3 Frequency Number of Hats Owned 12 4–6 18 7– –3 4–6 7–9 Number of Hats Owned Frequency Number of Hats