Spring 2022 • You may use a calculator, but if you plan to use a graphing calculator, you must clear the memory and show me evidence that you have done so before the exam. • The exam lasts 50 minutes....

From the study below: (a) Who or what are the observational units? (b) Identify the explanatory and response variables and their types? (c) Can the results of the study be used to to establish casual relationships? Explain.

Extracted text: Spring 2022 • You may use a calculator, but if you plan to use a graphing calculator, you must clear the memory and show me evidence that you have done so before the exam. • The exam lasts 50 minutes. • You must show all of your work and explain your answers to get credit. • If you do not know the answer, write down what you do know; you may receive partial credit. 1. In a public health study on the effects of consumption of fruits and vegetables on psychological well-being in young adults, participants were randomly assigned to three groups: (1) in one group, participants ate their usual diet, * (ii) in a second group, participants received text message reminders to increase fruit and vegetable consumption plus a voucher to purchase fruits and vegetables, (iii) and in a third group, participants were given two additional daily servings of fresh fruits and vegetables to consume on top of their normal diet. Participants, who were student volunteers at the University of Otago, New Zealand, were asked to ake a nightly survey on their smartphones. Four of the questions "Did you feel full of life?" , “Did you ave a lot of energy?" “Did you feel worn out?", and "Did you feel tired" were meant to assess the articipant's vitality, and the participant's responses to these four questions were converted to a score etween 0 and 100 measuring the participant's vitality. At the end of the 14-day study, only participants group (iii) showed improvements in their vitality score across the 14 days.