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# Rehab Research

### Chapter 20- Statistical Reasoning

Question | Answer |
---|---|

What is statistics? | a discipline in which mathematics and probability are applied in ways that allow researchers to make sense of their data |

What is a frequency distribution? | a tally of the number of times each score is represented in a data set |

What are the four ways to represent a frequency distribution? | 1. frequency distribution with percentages, 2. grouped frequency distribution with percentages, 3. frequency histogram, and 4. stem-and-leaf plot |

How is the central tendency represented? | mean, median, and mode |

What is the variability of a data set? | the amount of spread in the data |

How is variability represented? | range, variance, standard deviation |

What is a normal curve? | a symmetric frequency distribution that can be defined in terms of the mean and standard deviation of a set of data |

How is normal distribution represented? | z Score and percentages of the normal distribution |

What is sampling distribution? | a specific type of normal distribution |

How is significant difference represented? | with a null hypothesis |

What is the conventional level of chance that is tolerated (alpha level)? | 0.05 or 5% |

What information is needed for the determination of statistical probabilities? | the magnitude of the differences between groups, the variability within a group, and the sample size |

What is the effect size? | the between-group difference divided by a pooled version of the SD of the groups being compared |

What is the purpose for determining effect size? | allows the relative magnitude of experimental effects to be compared across variables with different measurement characteristics |

What is a Type I error? | if the statistical conclusion is that there is a difference between groups when in fact there is no difference |

What is a Type II error? | occurs when the statistical conclusion is that there is no difference between the groups when in reality there is a difference |

What is the probability of Type II error? | beta |

What is the power of a test? | the likelihood that it will detect a difference when one exists; 1 - beta |

What are the four major threats to statistical conclusion validity? | low power, lack of clinical importance, error rate problems, violated assumptions (and a fifth, failure to use intention-to-treat analysis) |

Created by:
amwilliamson