====== The concept of confidence intervals ======

The interval covers the true parameter with a probability $1-\alpha$ or the true parameter lies in the interval with a probability $1-\alpha$?

===== Animation =====

<ani ci http://s288.photobucket.com/albums/ll181/xieyihui/confidence_interval/ png 100 400 0.15|Demonstration of Confidence Intervals>
This animation shows the concept of the confidence interval which depends on the observations: if the samples change, the interval changes too. At last we can see that the coverage rate will be approximate to the confidence level.
</ani>

===== R code =====

<code r>
ani.options(ani.height = 400, ani.width = 600, outdir = getwd(), nmax = 100,
    interval = 0.15, title = "Demonstration of Confidence Intervals",
    description = "This animation shows the concept of the confidence
    interval which depends on the observations: if the samples change,
    the interval changes too. At last we can see that the coverage rate
    will be approximate to the confidence level.")
ani.start()
par(mar = c(3, 3, 1, 0.5), mgp = c(1.5, 0.5, 0), tcl = -0.3)
conf.int()
ani.stop() 
</code>