Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

Normal Size Small Size show me how

Normal Size Small Size show me how

# Stats Ch. 9

### Statistics for the Behavorial Sciences 9th Edition Chap. 9

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

(Sm) used as an estimate of the real standard error (Om), when the value of O is unknown. Computed from the sample variance or sample standard deviation and provides an estimate of the standard distance between a sample mean M and the population mean U. | estimated standard error |

used to test hypotheses about an unknown population mean, U, when the value of O is unknown. | t statistic |

describes the number of scores in a sample that are independent and free to vary. (n -1) | degrees of freedom |

the complete set of t values computed for every possible random sample size (n) or a specific degrees of freedom (df). Approximates the shape of normal distribution. | t distribution |

Under what circumstances is a t statistic used instead of a z-score for a hypothesis test? | A t statistic is used instead of a z-score when the population standard deviation and variance are not known. |

A sample of n=9 scores has SS = 288. Compute the variance for the sample. | 36 |

A sample of n=9 scores has SS = 288. Compute the estimated standard error for the sample mean. | 2 |

True or False. In general a distribution of t statistics is flatter and more spread out than the standard normal distribution. | True - As sample size and df increase, the variability in the t distribution decreases, and more closely resembles a normal distribution. |

A researcher reports a t statistic with df = 20. How many individuals participated in the study. | n = 21 |

For df=15, find the value(s) of t associated with the top 5% of the distribution. | +1.753 |

For df=15, find the value(s) of t associated with the middle 95% of the distribution. | +-2.131 |

For df=15, find the value(s) of t associated with the middle 99% of the distribution. | +-2.947 |

Sample = n=4, U=40 Treatment sample = M=44, variance s2=16. Is this sample sufficient to conclude that the treatment has a significant effect? | No - Fail to reject H0, treatment does not have a significant effect |

Sample = n=4, U=40 Treatment sample = M=44, variance s2=16. If all factors remained constant and sample size increased to n = 16, is sample sufficient to prove significant effect? | Yes, Reject NO. Treatment has significant effect. |

an interval or range of values, centered around a sample statistic. | confidence interval |

If all other factors are held constant, an 80% confidence interval is wider than a 90% confidence interval. (True or False?) | False - Greater confidence requires wider interval. |

If all other factors are held constant, a confidence interval computed from a sample of n=25 is wider than a confidence interal computed from a sample of n = 100. | True. The smaller sample produces a wider interval. |

Created by:
iAshee