Statistics

• Types of data


  Numerical and categorical
• Categorical data is:


  Questions that cannot be answered with numbers provide categorical data
• Numerical Data


  Questions that can be answered with numbers provide numerical data
• Two types of numerical data

  Discrete and continuous
• Continuous numerical data


  Any number between two numbers eg 1.7
• Discrete numerical data


  Whole numbers
• Two types of categorical data


  Ordinal and nominal
• Ordinal data


  Can be ordered in some way
• Nominal data


  Cannot be ordered
• Primary data


  Data collected by an individual or organisation for their own use
• Secondary data


  Data that is already available or has been collected by somebody else for a different purpose
• Population


  Entire group being studied
• Sample


  Portion of population selected for data
• 1 Method of Sampling


  Simple random sampling
• Simple Random Sampling


  Each member of the population is given an equal chance of being selected.

  This could be done by using a computer program to randomly select sample from population.
• Nominal categorical data


  Categorical data that cannot be ordered in any helpful way (e.g. nationality)
• Ordinal categorical data


  Categorical data that can be ordered in some way (Grades: A,B, C...)
• bar graph

  A graph that uses horizontal or vertical bars to display data

  
• categorical data

  Data that consists of names, labels, or other nonnumerical values

  
• data

  Facts and statistics collected together for reference or analysis

  
• Line Plot

  a graphical display of data using X
• Frequency

  The number of times an event happens
• frequency table

  a table listing each value that appears in a data set followed by the number of times it appears.

  
• numerical data

  Data that consists of numbers
• stem and leaf plot

  A display of data in which digits with larger place values are "stems" and digits with smaller place values are "leaves."
• survey

  to ask many people the same questions in order to gather data
• MEDIAN

  The middle number in a set of numbers that are listed in order

  
• MODE

  The number that occurs most

  
• RANGE

  The highest minus the lowest
• Mode

  The number that occurs most often in a set of data
• Range

  The difference between the highest and lowest number in a set of data
• Median

  The middle number
• Choosing a Suitable Chart

  • Charts are a very important means of presenting data
  • The chart that you use to present your data will depend on the type of data that you are working with and on the information that you want your audience to get from the data
• Line plots

  • Useful for data that is categorical or discrete numerical
  • Only suited to small data sets
• Bar charts

  • Useful for data that is categorical or discrete numerical
  • Can be used with large data sets
• Pie charts

  • Useful for data that is categorical
  • The relative size of each category can be seen from a pie chart
• Stem and leaf plots

  Suitable for small amounts of discrete numerical data or continuous numerical data that has been rounded
• Histograms

  Can be used to display continuous numerical data