Lesson 4

Statistics – Displaying Data There are various ways of displaying data collected from a survey. Graphs are a visual representation of data that are easy to read and interpret. However, not all graphs display data the same or as well. Choose a graph that best represents the data you have collected.

Histograms Purpose: used to display continuous data Appearance: Bars that touch each other with regular intervals on one axis and frequency on the other.( 5-8 bars is best ) Strength: Good for analyzing spread of data Weakness: Poor for seeing individual data (median, mode) and high and low values (extremes)

 Example: Test results for 30 students in a math class

Bar Graphs Purpose: used to display discrete data, and non-numeric data Appearance: Bars with spaces between which do not represent actual data. Regular intervals on one axis and frequency on the other. ( 5-8 bars is best ) Strength: Good for comparing results among the intervals of time or other quantities. Weakness: Poor for seeing individual data (median, mode) and high and low values (extremes)

 Example: Total sales of cars for each month of a year.

Stem and leaf Purpose: Used to display continuous data Appearance: displayed in the shape of a stem and leaf (sideways histogram) Strengths: Individual data readily available. Mode and median can easily be found. Mean can be calculated Weakness: Spread or dispersion around central data is not as easily read as other graphs. Not as pictorial as most other displays

Example: Age of 50 relatives coming to a family reunion StemLeaf 10,0,2,3,4,6,9 20,1,1,3,6,8 31,1,2,3,4 41,2,2

Box and Whisker Purpose: Used to display data dispersion around a median Appearance: Box in two parts with two whiskers Strengths: Displays extreme data as well as dispersion around the median. Great for comparing several data sets Weakness: Not able to determine the quantity of data displayed

Example: The results of 30 golf games for 2 players acting as alternates in a golf tournament.

Scatter Plot Purpose: Used to see if there is any correlation between 2 data sets Appearance: A series of dots between two axes of a graph Strengths: Best way to determine a positive, negative or non correlation between two sets of data Weakness: Interpretation not always easy

Example: The plotting of time spent studying against test results.

 Asn(A 10 ) Draw appropriate graphs for column 1,2,3,4 p. 135  Asn(A 11 ) Answer question 4 and 6 page 137. Use box and whisker for question 4.  Asn(A 12 ) Using graphics calculator for simulations of 10 draws 50 trials and 40% probability. Draw an histogram by hand for your data.  Asn(A 13 ) Using graphics calculator for constructing an histogram for the previous assignment   Statitistics- Test 1   Asn(B 1 ) Draw box and whisker plots for data on p.139. Answer questions 1 to 4 p. 139  Asn(B 2 ) Draw a histogram for the same data on p. 139  Asn(B 3 ) Answer questions 1 to 5 p. 139, 140  Asn(B 4 ) Read p Answer questions 9 to 13   Asn(B 5 ) Answer questions 16,17,18,19 p. 144  Asn(B 6 ) Answer 8 to 12 p.177  Asn(B 7 ) Answer 13 to 15 p. 177, 178   Statistics- test 2