 STATISTICS Statistical Terms    Back to Statistics Units

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 1For the following set of data find the mean, median,lowest and highest value: 2,4,6,8,10   answer 6,6,2,10 Question 2For 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 3Look 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 4Find 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 