Nayland College Mathematics  'More than just a school'  



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Overview The Statistical Cycle 1) A PROBLEM to investigate: Define the Problem, Define the Population, Define the Variables. 2) PLAN what variables and subgroups to compare and how to collect relevant statistics 3) DATA Collection: Organise the research, Decide on a sampling method, Collect the data. 4) ANALYSIS: Summarise data into tables, calculate measures of Central Tendency (averages: mean, median, mode) and measures of Spread (range, inter quartile range) 5) CONCLUSION: Comment on graphs, Comment on analysis, Draw conclusions, Suggest possible sources of error, Suggest improvements.

Achievement Standard  Overview  pg 276 pg 262 
pg 76, 77 
Problem"I wonder if there are differences between..." What information will you need to answer the question? Identify two or more subgroups of the population to compare. What variables are likely to show differences?


ConclusionRemember that you are analysing and comparing data from a SAMPLE from a population Is there a difference between the subgroups? Comparisons made from a BoxandWhisker graph Comparisons bases on measures of central tendency Comparisons made from measures of spread 
PlanIf collecting data you will need to plan a survey of questionnaire. Using available data sets is recommended If using a data set decide what subgroups of data are needed and choose from the available variables (choose carefully so you can answer the problem 

AnalysisAnalyse the data to find similarities and differences. You will need measures of central tendency (mean, median, mode) AND measures of spread (range, inter quartile range, standard deviation) Use technology to calculate the statistics: calculator, or EXCEL (using excel) Data displays Remember you are trying to compare your subgroups Essential:
BoxandWhisker Plot 
DataCollect data by making a survey or questionnaire, OR take a sample from large data set. (at least 30 values) eg Census at School or Gamma Maths Data Set Clean the data set before continuing





Statistics is about the collection and summarising of data from the world around us. Why? A ‘population’ is all the members of a group (eg all Y11 students in NZ) A ‘sample’ is a small group of a population (eg Y11 students in this class) We collect data from a sample because a population is too large to handle
A sample is a ‘snapshot’ of the population. 
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