1 (If you don't know what these, are set them each to 0.5. 2  z is the value that specifies the level of confidence you want in your confidence interval when you analyze your data. 3  Typical levels of confidence for surveys are 95%, in which case z is set to 1.96. 4  E sets the accuracy of your sample proportions.
Tests and diagnosis discussion for Gallstones: Many gallstones, especially silent stones, are discovered by accident during tests for other problems. But when gallstones are suspected to be the cause of symptoms, the doctor is likely to do an ultrasound exam. Ultrasound uses sound waves to create images of organs.
Gallstones are stone-like substances that are found in the gallbladder. There are two types of gallstones: pigment stones and cholesterol stones. In the majority of patients cholesterol stones are present. In many people the cause for gallstones appears to be interaction between hereditary causes and the diet.