Among a group of disabled women aged 65 and older who were tracked for several years, those who had a vitamin B12 deficiency were twice as likely to suffer severe depression as those who did not. (American Journal of Psychology 157 [2000]:715)a)Explain why this is an observational study and not an experiment. b)Who were the subjects of the study

The correct answer to this open question is the following.

According to your question, there are only two parts to be answered, a) and b).

Being that the case, we can comment on the following.

A) This is an observational study and not an experiment because the research was only limited to observation, participants never receive any kind of treatment or another interaction to experiment with them.

B) Who were the subjects of the study?

The subjects of this study were women aged 65 and older who were tracked for several years. The observation revealed that those women who had a vitamin B12 deficiency were twice as likely to suffer severe depression as those who did not.

So, according to the American Journal of Psychology, these were the women observed during the study. There were no more experiments, interactions, or activities applied to them in order to consider it an experiment.

Let's remember that in order to consider an experiment as such, there has to be another component of the study, and the experimental part of it that has to be tested and proved passing the scientific method to conclude in something valid.

uses : -

1.aneroid barometers primarily measure whether pressure is rising or falling.

2.aneroid barometers are often used for reading pressure in homes and recreational boats.  

3.other uses may include barographs in meteorology and altimeters in modern aircraft.  

4.this type of barometer can announce whether a high or low pressure system is coming or whether it is becoming more intense.  

5.there are different types of aneroid barometers, such as the altimeter, which measures altitude, or distance above sea level.  

6.another example is a barograph, which is a modified aneroid barometer that provides constant readings of atmospheric pressure on graph paper.  

7.when used in this capacity, the aneroid barometer can store a week's worth of data.

android diameter a device for measuring atmospheric pressure , often specially calibrated for use as an altimeter ,consisting of a box or chamber partially exhaused of air, having an elastic top and a pointer to indicate the degree of compression of the top caused by the external air

refer to the attachment for the characteristics : -