You are here: Vanderbilt Biostatistics Wiki>Main Web>StatCollabCourse>BosenbergSED (01 Oct 2012, MattShotwell)EditAttach

- SED Data (digitized from paper figure): Bosenberg1995.csv
- Scanned image from the Bosenberg (1995) paper: Bosenberg1995.png
- Digitized SED figure from the Bosenberg paper (Fig. 2): Bosenberg1995.svg
- Fitted linear regression line:
`SED = 3.93 + 0.80 * WT`

, where`SED`

is in mm units, and`WT`

is in kg units (R^{2}= 0.74). - From the paper:

Statistical methods: Regression analysis using the least squares procedure was used to determine the association between the skin-epidural distance and weight. For the difference between the two equations, i.e. the regression equation and the hypothesised 1 mm = 1 kg body weight, a Z-test was performed.In children over 10 years (n = 19) there was also poor correlation. The data from these patients were not used for further analysis.

Plotting the best fit regression line and its 95% confidence limits shows that the y = x line, or skin-epidural distance (mm) is equal to weight (kg) falls within these limits for weight <40 kg (or 10 years of age) in this series (Fig. 2). Therefore the difference between any two points on these two lines is not statistically significant.

In addition a Z-test performed on any two points obtained from the two equations for a specific weight, i.e. skin-epidural distance (mm) = 0.80 weight (kg) 3.93, and skin-epidural distance (mm) = weight (kg) was found to be not statistically significant.

...In summary, we have demonstrated that 1 mm/kg is a useful guideline for judging the skin-epidural distance in children between 6 months and 10 years of age.

- Was the confidence band really a prediction band?
- Was it simultaneous or pointwise?
- Was Bosenberg's reasoning sound?
- How can we verify Bosenberg's conclusions?

- Add Bosenberg's simplified prediction rule (i.e., 1 mm/kg) to the scatterplot.
- Modify the figure caption to reflect the addition above.
- Use a statistical technique to assess whether Bosenberg's simplified rule was reasonable.
- Add a short discussion of your findings.

I | Attachment | Action | Size | Date | Who | Comment |
---|---|---|---|---|---|---|

Rnw | Bosenberg.Rnw | manage | 4.2 K | 01 Oct 2012 - 08:51 | MattShotwell | Solution to the Bosenberg assignment |

Bosenberg.pdf | manage | 89.3 K | 01 Oct 2012 - 08:52 | MattShotwell | Solution to the Bosenberg assignment | |

png | Bosenberg1995.png | manage | 38.6 K | 17 Sep 2012 - 07:56 | MattShotwell | Scanned image from the Bosenberg (1995) paper. |

svg | Bosenberg1995.svg | manage | 185.3 K | 16 Sep 2012 - 10:02 | MattShotwell | Digitized SED data from Bosenberg (1995) paper |

Edit | Attach | Print version | History: r4 < r3 < r2 < r1 | Backlinks | View wiki text | Edit wiki text | More topic actions

Topic revision: r4 - 01 Oct 2012, MattShotwell

Copyright © 2013-2017 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.

Ideas, requests, problems regarding Vanderbilt Biostatistics Wiki? Send feedback

Ideas, requests, problems regarding Vanderbilt Biostatistics Wiki? Send feedback