What does a one sided confidence interval mean?
A one-sided confidence interval quantifies our knowledge about the true population mean by bounding the range of likely values on one side of the sample mean. In general, use a one-sided confidence interval instead of a two-sided confidence interval to obtain the tightest upper (lower) bound on a sample mean.
Can the confidence interval be negative?
The 95% confidence interval is providing a range that you are 95% confident the true difference in means falls in. Thus, the CI can include negative numbers, because the difference in means may be negative.
Do confidence intervals have to be binomial?
In other words, a binomial proportion confidence interval is an interval estimate of a success probability p when only the number of experiments n and the number of successes nS are known. There are several formulas for a binomial confidence interval, but all of them rely on the assumption of a binomial distribution.
When to use a one-sided or two sided test?
This is because a two-tailed test uses both the positive and negative tails of the distribution. In other words, it tests for the possibility of positive or negative differences. A one-tailed test is appropriate if you only want to determine if there is a difference between groups in a specific direction.
How do you interpret a negative confidence interval?
If the t value is negative, then the confidence intervals will also contain negative numbers. So long as the confidence interval does not cross zero (does not contain one positive and one negative number), it will be much easier to interpret it if you use the absolute value of the confidence interval.
What does it mean if 0 is not in the confidence interval?
If your confidence interval for a difference between groups includes zero, that means that if you run your experiment again you have a good chance of finding no difference between groups.