even4void

# Some illustrations of reliability analysis.
# Time-stamp: <2010-10-17 21:35:51 chl>
x <- c(12,8,22,10,10,6,8,4,14,6,2,22,12,7,24,14,8,4,5,6,14,5,5,16)
GHQ <- data.frame(subject=gl(12,1,24), time=gl(2,12), score=x)

# ----------------------------------------------------
# Computing reliability (Rx) by hand from ANOVA tables 
# ----------------------------------------------------
# one-way ANOVA (assuming no time trends)
summary(aov(score ~ subject, data=GHQ))

even4void

import graph;
import patterns;

size(300,200,IgnoreAspect);

real xmin=-4,xmax=4;
real ymin=0,ymax=1;
real PI=3.141593;
real sd=.6;
real a=1, b=-.5;

even4void

import graph;
import patterns;

size(300,200,IgnoreAspect);

real xmin=-4,xmax=4;
real ymin=0,ymax=1;
real PI=3.141593;
real sd=.6;
int a=-1, b=1;

even4void

import graph;
import patterns;

size(300,200,IgnoreAspect);

real xmin=-4,xmax=4;
real ymin=0,ymax=1;
real PI=3.141593;
real sd=.6;
int a=-1, b=1;

even4void

cronbach.alpha <- function(data, na.action="omit", signif.level=.05) {
  # computes Cronbach's Alpha
  # * Input *
  #    data         : a n*k matrix, where each column hold one item responses'
  #                   vector
  #    na.action    : if "omit", then handle missing value in cov/var
  #                   calculation [default]
  #    signif.level : type I error
  # * Output *
  #    a list with statistic and confidence interval

even4void

# Time-stamp: <2010-09-06 19:09:25 chl>

#
# Show multiple boxplot on the same page.
# Part of the code (esp. that concerned with making a bxp
# from scratch comes from P. Murrell.
#

#x <- replicate(50, sample(1:5, 500, rep=TRUE))
x <- replicate(190, rnorm(500))

even4void

#!/usr/bin/env python
from pylab import *
  
dt = 0.0005
t = arange(0.0, 20.0, dt)
s1 = sin(2*pi*100*t)
s2 = 2*sin(2*pi*400*t)
  
# create a transient "chirp"
mask = where(logical_and(t>10, t>12), 1.0, 0.0)

even4void

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(void) {
  char * line = NULL;
  size_t len = 0;

even4void

#! /usr/bin/env ruby
require 'statsample'
sample=200
a=sample.times.collect {rand}.to_scale
b=sample.times.collect {rand}.to_scale
c=sample.times.collect {rand}.to_scale
d=sample.times.collect {rand}.to_scale

ds={'a'=>a,'b'=>b,'c'=>c,'d'=>d}.to_dataset

even4void

#!/usr/bin/env ruby
require("gsl")

x = 2.0

P = GSL::Cdf::ugaussian_P(x);
printf("prob(x < %f) = %f\n", x, P);

Q = GSL::Cdf::ugaussian_Q(x);
printf("prob(x > %f) = %f\n", x, Q);