A 37 year old man is injured and has significant blood loss Following blood transfusion his systolic blood pressure increases from 70 to 100 Which physiological parameter is most likely to decrease in response?

You have designed a randomised control trial and need to make a calculation as to the sample size required such that we do not reject the null hypothesis when it is false Which component of the sample size calculation is most likely to avoid this error'?

A 67 year old man presenls one month post resection for cancer with breathlessness He is found to have iron deficiency anaemia Resection of what part of the gastrointestinal tract is most likely to be responsible for this deficiency''

You review a paper where patients were recruited through a response to an invitation from a heart foundation charity.
What term best describes this sample?

A 24 year old woman is admitted to your observation ward with a sudden onset headache. Her CT showed no abnormality and you decide to perform a lumbar puncture What is the next structure the needle will puncture after going through the skin and subcutaneous fat?