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# Pscyhology B5

### Chapter 3, 4 and 5

Term | Definition |
---|---|

Variability | The amount of spread or dispersion in a set of scores. |

Range | The highest minus the lowest score. This is a very general estimate. |

Exclusive Range | The highest score minus the lowest score |

Inclusive Range | The highest score minus the lowest score plus 1. |

Standard Deviation | The average amount of variability in a set of scores, or a measure of the average distance from the mean. This is the most common measure of variability, but it is sensitive to extreme scores. |

Variance | The square of the standard deviation. This measure is much more difficult to interpret than the standard deviation, which is why it is used much less often. |

Mean Deviation | The sum of the absolute value of the deviations form the mean divided by the number of scores. This calculation differs from that of the standard deviation. |

Unbiased estimate | An estimate of a population parameter in which 1 is subtracted from n. It is considered to be a more conservative estimate than the biased estimate. |

Frequency Distribution | A method of tallying and representing how often certain scores occur. Frequency distributions generally group scores into class intervals or ranges of numbers. |

Class Interval | A range of numbers, chosen by the researcher, to be used in charts/graphs. |

Histogram | A graphical representation of a frequency distribution in which the frequencies are represented by bars. |

Midpoint | The central point of a class interval. |

Frequency Polygon | A continuous line that represents a frequency distribution |

Cumulative Frequency Distribution | A frequency distribution that shows frequencies for class intervals along with the cumulative frequency for each. |

Otive | Another name for a cumulative frequency polygon. |

Column charts | A type of chart in which categories are organized horizontally on the x-axis and values are shown vertically on the y-axis. This type of chart is used to compare the frequencies of different categories with one another. |

Bar charts | A type of chart in which categories are organized vertically on the y-axis and values are shown horizontally on the x-axis in the form of separate, separated bars. |

Line Chart | A type of chart in which categories are organized vertically on the y axis and values are shown horizontally on the x-axis. These values are connected by one or more lines. |

Pie Chart | A type of chart that illustrates the proportions of responses to another item as a series of wedges in a circle. |

Correlation coefficient | A numerical index that reflects the relationship between two variables. |

Pearson Product-moment correlation | A specific type of correlation coefficient developed by Karl Pearson. It is specifically suited to determining the correlation between two continuous variables. |

Direct Correlation | A positive correlation such that the values of both variables change in the same direction. |

Indirect correlation | a negative correlation such that the values of the two variables move in opposite directions. |

Scatterplot or scattergram | a plot of matched data points. This type of chart is used to illustrate a correlation between two variables. |

Linear Correlation | A correlation that is best expressed as a straight line. |

Curvilinear Relationship | A situation in which the correlation between two variables begins as a direct correlation and then becomes an indirect correlation, or vice versa. It can be detected by examining the scatterplot. |

Coefficient of determination | The amount of variance accounted for in a relationship between two variables. |

Coefficient of alienation | the amount of unexplained variance in a relationship between two variables. It is equal to 1 minus the coefficient of determination. |

Phi Coefficient | A measure used to estimate the correlation between one nominal and one interval variable. |

Spearman rank coefficient | A measure used to estimate the correlation between two ordinal variables. |