| | __Data__
Includes: **Definitions, Example**
Data are observations or facts that can become information or knowledge |

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| | __Index__
Includes: **Definition:, What do indexes tell you?, How can we calculate an Index?, When is an index not appropriate?**
An Index is a number used to show the variation in some quantity over time. |

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| | __Mean__
Includes: **Definition , Here's another way of looking at it!, How do you calculate the mean?, When is the Mean not a useful measure?**
The mean is a summary number that measures the midpoint of a dataset. |

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| | __Measures of Error and Spread__
Includes: **Definitions, Calculations, Using Standard Deviation, Standard Error and Relative Standard Error**
Standard deviation measures the scatter in a group of observations |

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| | __Median__
Includes: **Definition, What can the Median tell you?, How do you calculate a Median?, When is the Median not a good measure of central tendency?**
The median is the middle score that seperates the lower half of a dataset from the higher half. |

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| | __Mode__
Includes: **Definition , What does the mode tell you?, How do you calculate a mode?, When is the mode not a good measure of central tendency?**
The mode is the most commonly observed data item in the data set |

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| | __Percentage__
Includes: **Definition, What does Percentage tell you?, How do you calculate the Percentage?, Benefits and downfalls of Percentage**
Percentage is a term used to express a number as a fraction of 100. |

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| | __Population, Sample and Estimate__
Includes: **Definitions, What do populations and samples tell us?, Which to use in a survey - Population or Sample?**
A population is any entire group with at least one common characteristic. |

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| | __Probability__
Includes: **Definition, What can Probability tell you?, How do you calculate Probability?, Benefits and downfalls of Probability**
Probability refers to the liklihood (or chance) of an event occuring. |

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| | __Quantitative and Qualitative__
Includes: **Definitions, Example**
Qualitative data describes an objects attributes that cannot be measured with numbers. Quantitative data is data characterised by numbers. |

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| | __Range__
Includes: **Definition, What does the Range tell you?, How is the Range calculated?, Benefits and downfalls of using the Range**
Range represents the distance between the highest and lowest values of a data set. |

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| | __Rate__
Includes: **Definition:, What does Rate tell you?, How is the Rate calculated?**
Rate is an expression of ratio; it represents the relationship between two numbers. |

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| | __Ratio__
Includes: **Definition, What does Ratio tell you?, How do you calculate the Ratio?**
Ratio is a way of concisely showing the relationship of one quality relative to another. |

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| | __Time Series__
Includes: **Definition- Time series, Why are Time-series Created?, Definition- Seasonally Adjusted Time-series, Why are Time-series Seasonally Adjusted?, Definition- Trend Time-series, Why are Trend Time-series Created?, Take care when using Time series**
A time series is a collection of observations obtained through repeated measurements through time. |

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