             data.push({x:x[j], y:dnorm(x[j], mu[i], sigma)})
 
         figs[0].append("path")
+               .attr("class", "curves")
                .datum(data)
                .attr("d", curve(0))
                .attr("fill", "none")

    n:
        text: "sample size per group, <em>n</em>"
        min: 2
        max: 1000
        step: 1
        value: 100
    delta:
        text: "effect, &Delta;"
        min: 0

    alpha:
        text: "significance level, &alpha;"
        min: -4
        max: -0.6
        step: 0.01
        value: Math.log10(0.05)

