Confidence interval crosses 0 vs 1

1. What does it mean when the confidence interval crosses 0?
2. What does it mean if the confidence interval crosses 1?
3. What does it mean if confidence interval does not cross 1?
4. Should a confidence interval include 1?

What does it mean when the confidence interval crosses 0?

If your confidence interval for a correlation or regression includes zero, that means that if you run your experiment again there is a good chance of finding no correlation in your data.

What does it mean if the confidence interval crosses 1?

Confidence interval (CI)

If the confidence interval crosses 1 (e.g. 95%CI 0.9-1.1) this implies there is no difference between arms of the study.

What does it mean if confidence interval does not cross 1?

If the confidence interval does not cross the line of no difference than the observed difference is statistically significant, because you know it is highly unlikely that the two groups are the same.

Should a confidence interval include 1?

If the confidence interval includes or crosses (1), then there is insufficient evidence to conclude that the groups are statistically significantly different (there is no difference between arms of the study).