Lab 4 Stats
Matthew Grattan

Why did you select the graph you did?

I chose the histogram because it clearly depicts the data best.


Is there anything interesting in the summary stats? WHat appears to be the general trend of the class for hours slept.

There was one person who gets 0 hours of sleep and one person who gets 20 hours of sleep. Most of the class gets roughly 7 hours of sleep for the most part.


Describe the shape of the hours of sleep the class gets. Are there any outliers? How do you know?

The shape is bell shaped with outliers at 0 hours, 1 hour, 13 hours and 20 hours. The box plot showed the outliers clearly.


Which graph for test 1 did you find most helpful? Why? Address each graph and indicate what you found useful or lacking in each one.

The stem and leaf plot was most helpful because it showed the distribution with numbers providing a nice visual. The dot plot was the least helpful because it was cluttered. The histogram showed the distribution, but not quite as well as the stem plot.


What is the shape of the histogram? Is the shape something you expected (or would expect) in our test results? Why or why not? Do you think every college class has this same type of distribution? Why or why not?

The histogram is skewed left. Yes because most people are going to study for the test and do their best on the test. No because some classes are harder than others/


Using the sidebyside boxplots for grades, describe the shape of the distribution for the HW scores. Are there any outliers for either set of scores? If so, indicate the score(s) of the outlier(s) for each. Using the IQR, which set of scores has more dispersion? Why you think that might be?

The homework scores are skewed left but more so than the test scores. There are outliers on both data sets for Hw: 73.67, 74.86, 78.82, 79.11, & 115.19. Test: 0, 40, 48, & 49. Test scores have a greater dispersion, on homework you can retry problems you missed to get a better score on homework you can't.


By inspection, determine whether you think the scatter plot indicates if a linear relation between HW and Test 1 scores exists. Why or why not? Now, compute the linear correlation coefficient yourself and compare it to the critical value in Table A2. Is there or not a linear relation between the two sets of scores? Why do you think that is the case?

No based on the scatter plot there is no relationship between homework and test scores. (.231 = r) no there is no linear relationship between test scores and hw scores.


Lastly, calculate your zscore for this last exam (meaning the value of x in the z formula is your individual test score). What does your zscore mean? Are you satisfied with your zscore? Why or why not?

Z = .2405 positive score means above average which is good and I’m satisfied with it.

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