# confidence intervals

### Confidence Regions for Regression Coefficients

September 16, 2012 |

Let’s consider the usual linear regression model, with the full set of assumptions:                     y = Xβ + ε ;    ε ~ N[0 , σ2In] , (1)where X is a non-random (n × k) mat...

### Plotting 95% Confidence Bands in R

July 26, 2012 |

I am comparing estimates from subject-specific GLMMs and population-average GEE models as part of a publication I am working on. As part of this, I want to visualize predictions of each type of model including 95% confidence bands. First I had to ma...

### Example 9.14: confidence intervals for logistic regression models

November 15, 2011 |

Recently a student asked about the difference between confint() and confint.default() functions, both available in the MASS library to calculate confidence intervals from logistic regression models. The following example demonstrates that they yield d...

### Plotting grouped data vs time with error bars in R

October 31, 2011 |

This is my first blog since joiningR-bloggers. I’m quite excited to be part of this group and apologize if I boreany experienced R users with my basic blogs for learning R or offendprogrammers with my inefficient, sloppy coding. Hopefully writing for...

### Test Difference between Two Proportions & Plot Confidence Intervals

August 11, 2011 |

..an illustrative example for testing proportions and presenting the results.the data: number of indigenous and alien plant species with and without vegetative reproduction. Hypothesis: The proportion of species with vegetative reproduction is differen...

### Bayesian Confidence Intervals: Obama’s ‘That’-Addition and Informality

May 1, 2011 |

No “That” Left Behind? I came across a post on Language Log last week giving some evidence that Obama tends to add that to the prepared version of his speeches. For example, in a recent speech at George Washington University, … Continue reading → [Read more...]

### Fit Sigmoid Curve with Confidence Intervals

April 28, 2011 |

Sigmoid curve fitting for transpiration measurements from porometer at different water potentials (pressure):Read more »

### Survival paper (update)

January 13, 2011 |

In a recent post, I discussed some  statistical consultancy I was involved with. I was quite proud of the nice ggplot2 graphics I had created. The graphs nicely summarised the main points of the paper: I’ve just had the proofs from the journal, and next to the graphs there ...