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 pieces of solid material that form in the gallbladder. These stones develop because cholesterol and pigments in bile sometimes form hard particles. The two main types of gallstones are: 1  Cholesterol stones: Usually yellow-green in color, approximately 80% of gallstones are cholesterol stones. 2  Pigment stones: These stones are smaller and darker and are made up of bilirubin.