What command is used to obtain double interval from normal interval?

To obtain a double interval from a normal interval in statistical analysis, you can use the command for confidence intervals, typically found in statistical software. For example, in R, you can use the t.test() function and specify the conf.level parameter as 0.95 for a normal interval, and 0.99 for a double interval. In Python, the scipy.stats library's t.interval() function can be utilized similarly to compute intervals with different confidence levels. Adjusting the confidence level effectively changes the width of the interval.