Using the fitted regression model, estimate the average change in cry time for infants with severe pain versus those without severe pain, holding group constant. Provide a 95% confidence interval for this estimate.
To estimate the average change in cry time for infants with severe pain compared to those without severe pain while holding the group constant, you would need to perform a regression analysis using the fitted regression model. Here are the general steps to obtain the estimated average change and the associated confidence interval:
1. Obtain the regression model that was fitted to the data. This would typically involve running a regression analysis, such as linear regression or logistic regression, using appropriate statistical software.
2. Check if the model includes a variable indicating severe pain. If it does, you can proceed to the next step. If not, you may need to modify the model or fit a new one that includes this variable.
3. Identify the coefficient estimate associated with the severe pain variable from the regression model. This coefficient represents the average change in cry time for infants with severe pain compared to those without severe pain.
4. Calculate the standard error (SE) of the coefficient estimate. The standard error reflects the uncertainty or variability of the coefficient estimate.
5. Using the coefficient estimate and its standard error, calculate the confidence interval. A common approach is to use the t-distribution and a desired level of confidence, such as 95%, to determine the range within which the true average change in cry time is likely to fall.
To calculate the confidence interval, you would typically use the formula:
Confidence interval = Coefficient estimate ± (Critical value * Standard error)
The critical value depends on the desired level of confidence and the degrees of freedom. For a 95% confidence interval with a large sample size (typically >30), the critical value can be obtained from a standard t-distribution table or t-distribution function in statistical software.
By following these steps, you should be able to estimate the average change in cry time for infants with severe pain versus those without severe pain, while holding the group constant, and obtain a 95% confidence interval for this estimate.