Maths- statistics 1

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  • Created by: shona
  • Created on: 26-12-12 16:13
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  • Maths- statistics 1
    • averages and range
      • mode
        • most common
      • median
        • the middle number once arranged in order
      • mean
        • the sum of all values divided by the total number of values in the set
          • mean= sum of all values/ total number of values
      • range
        • the difference between the highest and lowest values in a set
          • range= highest-lowest
    • frequency tables
      • when data is represented it can be put in a frequency table
      • find the mode by looking for the data value that has the highest frequency
      • find the median by adding up all the frequencies in order until half way point of all data is passed
      • find the mean by multiplying the value of each data by its frequency adding the totals and dividing by the total of all the frequencies
    • grouped data and frequency diagrams
      • when there is a wide range of data with lots of values there are often too many entries for the frequency table
        • so you will use a grouped frequency table
      • in a grouped frequency table data is recorded in groups like 10< x<20
      • grouped data can be shown in a frequency polygon
      • the modal class is the group with the greatest frequency
      • median cannot be found from grouped frequency tables
      • calculate an estimated mean by adding the midpoints multiplied by the frequencies and dividing by the total frequency
    • histograms
      • similar to a bar chart but continuous data only ( time or weight)
      • the horizontal axis
        • has the continuous scale and there are no gapes between the bars
      • the area of each bar represents the frequency of the bar
      • the height of the bar is called the frequency density
        • frequency density= frequency class interval/ width of class interval
      • the median is the value where the area of both is equal
      • the lower quartile is the value that splits the area in the ratio 1:3
      • the upper quartile is the value that splits the area in the ratio 3:1
    • the data handling cycle
      • outlining the problem and planning
        • usually involves a hypothesis
      • stating how the data will be collected
      • saying how the data will be processed and represented
        • usually involve working out means and measures of spread and showing the data in a suitable diagram
      • interpreting the results and making a conclusion
        • this should relate to the original hypothesis or problem
    • data and data collection
      • qualitive
        • this is data such as colour of cars
      • discrete quantative
        • this is numerical data that can only take certain values such as the number of people on a bus
      • continuous quantative
        • this is numerical data that can take any value in a range of values such as the weight of apples
      • primary data
        • this is data collected using surveys or experiments
      • secondary data
        • this is data collected from existing tables or lists
      • look at historical data
        • this would be used to predict whether it will rain on the 4th july in Edinburgh for example you would look back at records for all previous years
      • experiment
        • this would be used to test the probability of an event that cannot be predicted such as how many blue balls in a bag
      • equally likely outcomes
        • this is used when the probability of an event can be predicted for example taking a king from a pack of cards
      • surveys
        • this is used when there is no historical data and no way to predict probabilities a survey could be used to find what subject is the favourite amongst year 7 pupils
  • when talking about the average its the same as the mean
  • the lower quartile is the value that splits the area in the ratio 1:3
  • there are four parts to the data handling cycle
  • usually involve working out means and measures of spread and showing the data in a suitable diagram
  • there are different types of data
  • depending on what is being investigated there are four different ways to collect data

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