我现在正试图估算进行A/B测试以提高网站转化率所需的样本大小。当我的转化率较小时,pwr.chisq.test总是给出错误消息:
# conversion rate for two groups
p1 = 0.001
p2 = 0.0011
# degree of freedom
df = 1
# effect size
w = ES.w1(p1,p2)
pwr.chisq.test(w,
df = 1,
power=0.8,
sig.level=0.05)
**Error in uniroot(function(N) eval(p.body) - power, c(1 + 1e-10, 1e+05)) :
f() values at end points not of opposite sign**
然而,如果我的p1和p2的值较大,这段代码就能正常工作。
# conversion rate for two groups
p1 = 0.01
p2 = 0.011
# degree of freedom
df = 1
# effect size
w = ES.w1(p1,p2)
pwr.chisq.test(w,
df = 1,
power=0.8,
sig.level=0.05)
Chi squared power calculation
w = 0.01 N = 78488.61 df = 1 sig.level = 0.05 power = 0.8
NOTE: N is the number of observations
?pwr.chisq.test
,"N:观测总数
"。 - Vincent Guillemot