Hello, i need to analyze an could you me?
stewart fist reported the results of an experiment investigating the link between cell phone use and tumors in mice. the study exposed 100 mice to cell phone radiation for 2 1/2 hour periods each day for 18 months. the researchers fitted another 100 mice with the same type of antennas, which never had the power turned on. the tumor rate was twice as high in the exposed group vs. the unexposed group.
i know the question, population and sample, but i am having trouble identifying potential bias or finding lurking variables. this experiment looks pretty clean to me.
you, scarlett

Aconcession manager at yankee stadium wants to know how temperature affects beer sales. she took a sample of 10 games and recorded the number of beers sold and the temperature in the middle of the game. temperature 80 68 78 79 87 74 86 92 77 84 number of beers 20533 1439 13829 21286 30985 17187 30240 87596 9610 28742 a. draw a scatter plot of the data. b. the manager estimates the regression equation to be: numberofbeers = −100, 678 + 1, 513 ∗ temperature draw this on your scatter plot. c. for one of the estimated points, indicate the residual with ei . d. for that same point, indicate what part of the variation is explained by the model with ˆyi − y¯.