No, don't use a single t-test to compare the means of 3 or more groups. Use ANOVA.
The sample standard error.
I use a "magnet".
They use a standard urine test.
Use %RSD when comparing the deviation for popolations with different means. Use SD to compare data with the same mean.
They use the standard laboratory urine test.
They have to use standard units of measurements in their expirements, so they can commpare data
The standard DOT test - pot, opiates, PCP, cocaine and amphetamines.
Hammer, Mallet. Also Youtube.
So that scientists all over the world can easily compare their results
The pH test paper is used to detrmine the pH; immerse a piece of paper in the solution and compare with the color scale.
To calculate the standard error of measurement, you can use the formula: SEM SD (1 - reliability). SEM stands for standard error of measurement, SD is the standard deviation of the test scores, and reliability is the reliability coefficient of the test. This formula helps estimate the amount of error in a test score measurement.