Question 4: Is the presence of a crisis plan related to other variables which might increase the risk of readmission, such as age, sex, number of previous admissions, pulse rate, or respiration rate? How do children given a crisis plan differ from the other children?

Sex is a qualitative variable, so we will use a cross-tabulation and chi-squared test.
Choose __Descriptive Statistics__, __Crosstabs__.
Put "Sex" into __Row(s):__ and "Crisis plan" into __Column(s):__.
Click __Statistics__, __Chi-square__.

Now we are ready, so __Continue__, __OK__.

We get the following output:

Sex * Crisis plan Crosstabulation | ||||
---|---|---|---|---|

Count | ||||

Crisis plan | Total | |||

Absent | Present | |||

Sex | Girl | 337 | 77 | 414 |

Boy | 539 | 80 | 619 | |

Total | 876 | 157 | 1033 |

Chi-Square Tests | |||||
---|---|---|---|---|---|

Value | df | Asymp. Sig. (2-sided) | Exact Sig. (2-sided) | Exact Sig. (1-sided) | |

Pearson Chi-Square | 6.199^{b} | 1 | .013 | ||

Continuity Correction ^{a} | 5.766^{ } | 1 | .016 | ||

Likelihood Ratio | 6.105^{ } | 1 | .013 | ||

Fisher's Exact Test | .013 | .009 | |||

Linear-by-Linear Association | 6.193^{ } | 1 | .013 | ||

N of Valid Cases | 1033^{ }
| ||||

a. Computed only for a 2x2 table | |||||

b. 0 cells (.0%) have expected count less than 5. The minimum expected count is 62.92. |

Clearly girls are more likely to have crisis plans than boys.

The other variables are all quantitative and, in view of the large sample size, a z test is indicated. We use the independent samples t test with unequal variances to get this.

Click __Analyze__, __Compare Means__, __Independent Samples T Test__.
Put "Age (years)", "Hours of wheezing", "Previous admissions", "Pulse (beats/min)",
and "Respiration (breaths/min)" into __Test variable(s)__ and "Crisis plan"
into __Group Variable:__.
Click __Define Groups__ and put 0 and 1 into the boxes, __Continue__, __OK__.
We get:

Group Statistics | |||||
---|---|---|---|---|---|

Crisis plan | N | Mean | Std. Deviation | Std. Error Mean | |

Age (years) | Absent | 874 | 3.7094 | 3.01660 | .10204 |

Present | 157 | 5.3439 | 3.76508 | .30049 | |

Hours of wheezing | Absent | 873 | 36.1615 | 67.92851 | 2.29903 |

Present | 155 | 43.6387 | 86.40533 | 6.94024 | |

Previous admissions | Absent | 876 | 2.00 | 5.732 | .194 |

Present | 154 | 6.73 | 6.392 | .515 | |

Pulse (beats/min) | Absent | 869 | 136.5201 | 20.86844 | .70791 |

Present | 154 | 133.2532 | 23.46087 | 1.89053 | |

Respiration (breaths/min) | Absent | 871 | 44.8875 | 13.18459 | .44674 |

Present | 149 | 41.2349 | 12.51561 | 1.02532 |

Independent Samples Test | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|

Levene's Test for Equality of Variances | t-test for Equality of Means | |||||||||

t | df | Sig. (2-tailed) | Mean Difference | Std. Error Difference | 95% Confidence Interval of the Difference | |||||

F | Sig. | Lower | Upper | |||||||

Age (years) | Equal variances assumed | 24.243 | .000 | -6.003 | 1029 | .000 | -1.63457 | .27231 | -2.16892 | -1.10021 |

Equal variances not assumed | -5.151 | 193.592 | .000 | -1.63457 | .31734 | -2.26045 | -1.00868 | |||

Hours of wheezing | Equal variances assumed | 5.872 | .016 | -1.208 | 1026 | .227 | -7.47720 | 6.18925 | -19.62223 | 4.66783 |

Equal variances not assumed | -1.023 | 189.250 | .308 | -7.47720 | 7.31112 | -21.89896 | 6.94457 | |||

Previous admissions | Equal variances assumed | 26.194 | .000 | -9.265 | 1028 | .000 | -4.724 | .510 | -5.724 | -3.723 |

Equal variances not assumed | -8.585 | 198.625 | .000 | -4.724 | .550 | -5.809 | -3.639 | |||

Pulse (beats/min) | Equal variances assumed | 3.799 | .052 | 1.756 | 1021 | .079 | 3.26689 | 1.86028 | -.38352 | 6.91731 |

Equal variances not assumed | 1.618 | 198.227 | .107 | 3.26689 | 2.01872 | -.71404 | 7.24782 | |||

Respiration (breaths/min) | Equal variances assumed | .546 | .460 | 3.148 | 1018 | .002 | 3.65259 | 1.16043 | 1.37548 | 5.92970 |

Equal variances not assumed | 3.266 | 208.251 | .001 | 3.65259 | 1.11842 | 1.44772 | 5.85746 |

Age, previous admissions, and respiration are significantly related to the crisis plan.

Children given a crisis plan were more likely to be girls than were other children, and tended to be older, to have had more previous admissions, and to have slower respiration.

Back to Exercise: Readmission to hospital for asthmatic children.

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Last updated: 5 April, 2007.