<qa>  What was the reason for selection less than 5 percent variation?The nurses were learned the theoretical and practical skills previously during their studentship period. The procedures will be the first time the nurses wanted to perform in ICU. All clinical situations including patient, procedure, and shift will be similar for nurses. The end point will be reaching to the 95 score of learning curve. The reason for selection less than 5 percent variation was the flattening of learning curve the plateau section. 