It cannot tell the exact reason, but to measure the same thing multiple times, it will have a different value. Even if the measuring instrument will be prepared and available under the appropriate environment, as.
It can not tell the exact cause. However, measuring the same thing many times, it has different values. The instruments are well prepared and used under the given environment.
It can tell the exact causes. But the same thing many times measurement to different values. Even though the instrument will be prepared well and use under the suitable environment.