That means that an increase of net exports of $100 million leads to an increase in real GDP of $1 billion. Again, this is the multiplier effect at work in the economy. When you think about it, the MPC and the MPS are the key to this formula. When they change, the multiplier effect changes. Since the simple spending multiplier is based on the marginal propensity to consume, any increase in the MPC will increase the value of the multiplier. Likewise, any decrease in the MPS will increase the value of the multiplier.
There are physical causes of shaking, but these tend to be less common. Only a doctor can confirm that you are feeling shaky because of anxiety and not because of some health problem. Also, during periods of stress, the body may deplete important resources, like water or magnesium.
WebMD lists a number of conditions associated with body shaking, including the flu in adults, viral syndrome and Parkinson's disease. An acute stress reaction or cold exposure also causing body shakes. WebMD also notes several other causes, including coxsackie virus infection and a rare disease called sarcoidosis.