title: High p-value but confidence interval that excludes 0?
body: <p>In an A/B test, I'm calculating the proportion of Group A that have done something and comparing to the proportion of Group B that have done something to see if there is a meaningful difference. I run a t-test and find that the difference of -30% has a p-value of ~0.99, so I fail to reject the hypothesis that these proportions are different. </p>
  
  <p>I want to show the 95% confidence interval around that difference and it's [-0.6238, 0.0084]. That's so close to not straddling 0, so I run a 90% confidence interval and it's [-0.5730, -0.0424]. </p>
  
  <p>How is it possible for the p value to be so high but the 90% confidence interval excludes 0? </p>