Here are two questions from a questionnaire administered to adults. How might you improve them? 'How much do you routinely spend on clothing and transport?' 'Which one of the following age groups are you in? 18 to under 30, 30 to under 45, 45 to under 60, Over 65.' Give an example of how a twophase sampling scheme which uses an auxiliary variable is operated. An auxiliary variable is one which is inexpensive to measure in the initial survey prior to the accurate second phase. Explain the difference, with examples, between open and closed questions