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require 'confidence_intervals'
describe "ci_bounds" do
describe "when passed all successes" do
it "should never return a high CI above 1" do
ci = ci_bounds 16, 16, 0.01
ci[1].should be <= 1
end
end
describe "when passed all failures" do
it "should never return a low CI below 0" do
ci = ci_bounds 0, 10, 0.05
ci[0].should be >= 0
end
end
describe "when passed 4 out of 10 successes (with 0.05 power)" do
it "should return the correct Wilson's interval" do
# The expected results here were taken from an online
# calculator:
# http://www.vassarstats.net/prop1.html
ci = ci_bounds 7, 10, 0.05
ci[0].should be_within(0.001).of(0.3968)
ci[1].should be_within(0.001).of(0.8922)
end
end
end
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