As a pa of space-research program, a physiologist was asked to investigate the effect of flight-induced stress on blood pressure. Accordingly, the blood pressure of the cosmonauts were to be measured twice: once before the takeoff and once after the spacecraft entered the designated orbit around the eah. For a proper comparison, the preflight blood pressure should be recorded in:
A i.e. The lying down position For two values to be comparable (to remove any bias) we must remove as many confounding variables as possible. The confounding variable in this question is gravity. Gravity is present on eah but is not present in space. The best position in which the effect of gravity is nullified is lying down.
The lying down position
The sitting position
The standing position
Any position, as long as the post-flight recording is made in the same position