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Statistics – What is it? Torture numbers, and they'll confess to anything. ~Gregg Easterbrook 98% of all statistics are made up. ~Author Unknown Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital. ~Aaron Levenstein Statistics can be made to prove anything - even the truth. ~Author Unknown Lottery: A tax on people who are bad at math. ~Author Unknown He uses statistics as a drunken man uses lampposts - for support rather than for illumination. ~Andrew Lang The theory of probabilities is at bottom nothing but common sense reduced to calculus. ~Laplace, Théorie analytique des probabilités, 1820 I could prove God statistically. Take the human body alone - the chances that all the functions of an individual would just happen is a statistical monstrosity. ~George Gallup Statistics are just a way for the mathematician to evangelize his faith. ~Hunter Brinkmeier There are three kinds of lies: lies, damned lies, and statistics.“ ~ Benjamin Disraelie
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The Different Ways of Describing Data
Discrete data Continuous data Categorical data Numerical data Qualitative data Quantitative data
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The Different Ways of Describing Data
Data that is digital and has specific values with gaps in between. A slight improvement in the accuracy of the measuring device does not alter the data. Discrete data Continuous data Categorical data Numerical data Qualitative data Quantitative data Data that is analogue and takes a range of values. A slight improvement in the accuracy of the measuring device alters the data collected. Data that falls into different labelled groups. If the labels are numerical then they have no numerical worth so calculating a mean is meaningless. Data that is based on the size of numbers where the size of the numbers have some meaning. Data that has been collected based on some quality or categorization that in some cases may be 'informal' or may use relatively ill-defined characteristics such as warmth and flavour; Data that can be observed but not measured. Data that has a been collected by using a measuring scale is data measured or identified on a numerical scale.
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Give 3 examples of each type of data:
Discrete data Continuous data Categorical data Numerical data Qualitative data Quantitative data
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The Different Ways of Describing Data
Discrete data Continuous data Categorical data Numerical data Qualitative data Quantitative data Eg Shoe Size, Dice score, Type of Pet Eg Time to run a mile, length of a hair Eg Types of Pet, House Number, Colour Eg Score on a dice, Weight of a lemon Eg I feel happy, The weather is good today Eg The score obtained in a test, the height of a tree
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Different Sampling Techniques
There are many different ways to generate a sample for data collection: 4 of the most common are: Random Sampling Systematic Sampling Stratified Sampling Convenience Sampling Look at the cards on the next slide and decide which sampling technique is being described. Think of an advantage and a disadvantage for the technique described.
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A pollster stands in Huntingdon market square and asks the first 30 people that will listen to her their opinions on a market revamp. In a survey to assess opinions about Year 10 uniform a school list is printed and every 10th pupil on the list selected. A bag contains 100 names. It is shaken and 30 names are drawn from the bag without looking At a local club it is known that ¾ of the membership is female. A sample of 21 females and 7 males is drawn by randomly picking names from a hat. To find out opinions about a web site you ask the first 30 people to visit the site to complete a questionnaire using their browser. To select a sample of 6 people from a class of 30 to do a maths test, the class are lined up in height order and every 5th pupil selected. A Secondary school has 3 Key Stages with pupils split between them in the ratio 3:2:3 To survey opinions about the school canteen they interview 30 students from KS3, 20 from KS4 and 30 from KS5. In a class of 20 pupils each pupil is assigned a number and 4 members are selected for a competition by using the random number generator on a calculator. To investigate the health of whales a marine biology charity decide to estimate the length of whales in the South Atlantic by measuring the first 10 whales they find.
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