Questions 1. Random sampling and random assignment sound similar, but this sim- ilarity is misleading. In actuality, they are different concepts used with dif- ferent goals in mind. Explain what random sampling is and why researchers use it. Explain what random assignment is and why researchers use it. Hint: Random sampling increases one type of validity and random assignment in- creases another type of validity. Please ensure your answer addresses both of these validities. 2. People often mistakenly believe that increasing sample size increases external validity. Why is this a mistake? What validity is actually increased by increasing sample size? 3. Alfred is a positive psychologist with expertise in the relationship be- tween exercise and happiness. He wants to encourage people to exercise be- cause research shows it is linked to increases in happiness. He conducts a survey comparing levels of exercise in two cities. City A has lots of bike. lanes; City B has no bike lanes. Alfred hypothesizes that bicycling will be more common in City A than City B. He obtains a list of every adult in City A and another list of every adult in City B. 1000 residents from each city are drawn at random from the larger list. Every selected person is then asked to estimate how many hours a week they spend bicycling. (M Results showed that significantly more time is spent bicycling in City A = 5.58, SD = 4.10) than City B (M = 3.65, SD = 6.13), t(1998) 8.28, p < .001. Figure 1 depicts the results graphically. a. What sampling technique did Alfred use? Explain. = b. Assuming that the populations of interest are adults living in Cities A and B, then was Alfred's study high or low in external validity? Explain. c. Imagine that Alfred concludes that bike lanes cause an increase in time spent bicycling. Would this causal claim be justified? Explain your answer Additionally, remember that any sources you consult excluding the textbook and slides must be cited. Hours Spent Bicycling N 10 Figure 1: Mean Time Spent Bicycling in Cities A and B City with reference to the criteria for causation.2 B