What is the critical z used to form a 85% confidence interval?
To determine the critical z value for a specific confidence interval, we need to refer to the z-table or use a statistical calculator.
Here's how you can find the critical z value for an 85% confidence interval:
1. Start by determining the level of confidence. In this case, the level of confidence is 85%.
2. Since the confidence interval is centered around the mean, we need to divide the confidence level by 2 in order to find the area in each tail. In this case, 85% divided by 2 gives us 42.5%.
3. We now need to find the z-value that corresponds to a cumulative probability of 1 - 0.425 = 0.575. This value represents the area to the right of the z-score.
4. Look up the z-value in the z-table or use a statistical calculator that can provide the desired z-value.
The resulting critical z-value for an 85% confidence interval is approximately 1.44.
Remember, z-values depend on the specific level of confidence you are looking for, so you will need to follow these steps to find the critical z-value for other confidence levels.