Homework Help for Statistics
Statistics is an area of Mathematics that uses large amounts of numerical data to make inferences based on probabilities.
72. What is the distinction between a linear relationship and a correlation between two variables?
73. If you are interested in whether variable X causes variable Y, what is the relevance of knowing the variables X and Y are correlated?
74. What is a spurious correlation? What do spurious correlations indication about the relationship between correlation and causation?
75. What is the relationship between correlation and prediction? What do we mean by a prediction model?
65. For this dataset, what is the correlation coefficient (r)?
66. What is the regression equation for this dataset?
67. Based on the model (i.e. the regression equation) you just made, predict the perceived pleasantness score for a person who has a percent occupancy score of 70.
|participants||percent occupancy||perceived enjoyment|
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55. What kind of hypothesis test will you use to analyze this dataset?
56. Using the .01 significance level, carry out a t test to test the experimenter's assumption that the participants' belief in the supernatural would change in some way after watching the movie.
53. What kind of hypothesis test will you use to analyze this dataset? (look at photo)
A program to decrease littering was carried out in four cities in California's Central Valley starting in August 2011. The amount of litter in the streets (average pounds of litter collected per block per day) was measured during July before the program started and then the next July, after the program had been in effect for a year. The results were as follows:
|City||July 2011||July 2012|
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15. What is the statistical power of STUDY A? (Bonus: How many additional subjects would be required to reach a minimum power of 0.80 for this study?)
16. What is the statistical power of STUDY B? (Bonus: How many additional subjects would be required to reach a minimum power of 0.80 for this study?)
17. Based of this comparison of STUDY A and STUDY B, which type of experimental design would you prefer for testing the memory effects of IGF2?
9. Based on your answer to the previous question, give an example of a cutoff score that would be statistically significant for one type of test (Z or t) but not the other.
10. Is it possible to perform a statistical test if the data being analyzed violates one of the test's assumptions? Why or why not?
6. For a two-tailed test with α = 0.05, what are the cutoff t values for a t-distribution with df = 30?
7. What is the relationship between sample size and cutoff t values?
8. Other factors kept constant, is it easier to reject the null hypothesis in a Z-test of a sample mean or a single-sample t-test?