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Collecting, presenting and interpreting information or data are activities that are of extreme importance in today's "information age".  The study of statistics includes these skills and hence enhances our social awareness and career opportunities.  Below are some terms that appear frequently in the work and everyday lives of people. Data Use of Data Display of Data

 

 

 

 

 

Examples

Here  we are providing some common terms and definitions used in statistics. Select the area you want to find terms and meanings in.

 

Data

Use of Data

Display of Data

 
                   
                   

 

 

 

 

 

DATA
Term	Explanation
data (i) discrete (ii) continuous	Information that is collected -data which are usually whole numbers(eg number of family members) -data that can take on any decimal value(eg height of student)
(i) census (ii) sample	Two types of Information Collection -survey of the whole population(eg population of Australia, or the population of your family -survey of a small proportion of the whole population, chosen randomly(sample of 100 fish from the bay) -sample size should be big enough not to be biased
bias	-the sample should be chosen so that each member of the population is equally likely to be chosen ie. so that there is no bias
random sampling	-selection of data so that no bias is introduced into the survey
score	-the tally of each value or number in the survey
USE OF DATA
Term	Explanation
range	-difference between the highest and lowest values in the sample
mean	-can be called average
median	middle score for an odd number of values or average of the middle two values for an even number of values
mode	value that occurs the most
Data may be grouped	Results or values grouped into classes
mean	-is calculated approximately using the class centres
median class	-is the class containing the middles score or scores
modal class	-is the class with the highest frequency
DISPLAY OF DATA
Term	Explanation
frequency histogram	-a column graph -the vertical axis shows the frequencies
cumulative frequency histogram or ogive	-a line graph -the vertical axis shows the cumulative frequencies -upper quartile(75% line for number of values) -median(50% line for the number of values) -lower quartile(25% line for the number of values)
five-number summary	lowest value lower quartile median upper quartile highest value
box plot	-pictorial representation of five-number summary

 

 

 

 

 

 

Have a Go Problem 1 Find the mean,median and mode for the following set of values(data): 2,2,2,3,3,4,4,4,4,5,5,6,6,6   Problem 2 Find the five-number summary for this set of data and construct a box-plot. 10,11,12,16,17,18,19,19,21,23

 

 

 

 

 

 

Practice Questions Question 1 For the following set of data find the mean, median,lowest and highest value: 2,4,6,8,10   answer 6,6,2,10 Question 2 For the following set of data find the mean, median,lowest and highest value: 2,4,6,8,10,20   answer 8.3, 8, 2, 20   Question 3 Look at Q1 and Q2.   In Q2 the value "20" is unusually large for the particular set of values.   Which is affected more by this extra value- the mean or median? answer mean   Question 4 Find the mean and median of this set of data: 1,2,3,4,5,6,7,8,9,10 Then remove "5" and "6" from the data and calculate the mean   and median. answer 5.5, 5.5, 5.5, 5.5

 

 

 

 

 

 

Solution 1 back to Have a Go

Solution 2 There is only a small number of data so instead of drawing a cumulative frequency histogram the data can be grouped to find the median, lower quartile and upper quartile. 10,11,12,16,17,||18,19,19,21,23 Lowest value:  10 25th percentile: 12 median(50th percentile): 17.5 75th percentile: 19 Highest value:  23   back to Have a Go

 

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