Lab 2-Graphing Data and Numerical Summaries_TRAN

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Feb 20, 2024

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Name: Tam Tran T.A. name: Chanhui Liu Lab 2: Graphing Data and Numerical Summaries NOTE: SPSS outputs are necessary to show full completion of the lab. Please paste all SPSS outputs into your lab report and submit the completed reports including all requested tables and graphs via Brightspace (under the "Lab" folder) by 11:59 pm Friday. Two points will be deducted for each SPSS requested output that is not included in the submitted lab document. Also, 30% points will be deducted for late submission, up to 24 hours. Dataset : This lab uses the dataset ( SleepPatterns ), located on Brightspace under Lab in the Datasets submodule. Instructions for opening the dataset in SPSS are found as follows.  SPSS installed on a computer: Reference page 4 of the SPSS Instruction Manual  SPSS running remotely: Reference the slide “Opening your Dataset Remotely in SPSS via Go Remote” in the document “SPSS using Citrix access guidelines” on Brightspace. Two hundred fifty college students in Indiana participated in a study examining the associations among sleep habits, sleep quality and physical/emotional factors. Participants completed an online survey about sleep habits that included the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Horne-Ostberg Morningness Eveningness Scale (MES), the Subjective Units of Distress Scale (SUDS), and questions about academic performance and physical health. 1. (2 points) Fill in the chart below. In the second column, record whether the variable is quantitative or categorical, based on the data in the lab dataset . In the third column record whether a bar graph or a histogram correctly shows the distribution of the data. Variable Name Type of variable Type of graph Sleep_time_week Quantitative Histogram Gender Categorical Bar graph Weight Quantitative Histogram Class Categorical Bar graph Age Quantitative Histogram 1

2. (2 points) Use SPSS to make a bar graph for the variable Gender . Copy and paste the graph into this document here . 3. (2 points) Use SPSS to make a histogram for the variable Sleep_time_week . Copy and paste the graph into this document here . 2

4. (2 points) Use SPSS to find the mean and standard deviation of Sleep_time_week . Record the values rounded to two decimal places below. Copy and paste t he SPSS output into this document here. Sleep_time_week: Mean: 7 Standard deviation: 0.50 Descriptive Statistics N Minimum Maximum Mean Std. Deviation Sleep_time_week 250 5.48 8.29 6.9994 .49930 Valid N (listwise) 250 5. (4 points) SPSS is not used in this course to find quartiles because the program’s default method yields an unbiased estimate of the population quartiles. Rather, in this course, the interest is to find quartiles associated with the sample. 3

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BY HAND , find the 5-number summary of Sleep_time_week . Show your work on how to find the location of Q1, Median and Q3. (You can use SPSS to sort the data from smallest to largest first, and use the row number on the left of the Data View tab to make the job easier). Min Q 1 Median Q 3 Max 5.48 6.67 7.01 7.33 8.29 5# summary for Sleep_time_week : 6. (2 points) Inspect the histogram for the variable Sleep_time_week created in Question 3. Is the graph approximately symmetric, skewed left, or skewed right ? Explain how the graph’s shape is related to the Mean and Median calculated in Questions 4 and 5. The histogram is approximately symmetric. If the histogram was skewed, then our mean would not have been an accurate measure of the center of distribution. We would then use the median of the histogram to determine the center of distribution. When the graph is skewed it means that the size of the data was too small or too large depending on if it is skewed left or right. A symmetric histogram would mean that the variables occur often at the same time and that the graph is almost split mirror image of its other half. 7. (2 points) BY HAND , use the 1.5*IQR Rule to determine if there are any suspected outliers for the variable Sleep_time_week . Show your work. State and explain why there are or not suspected outliers. If there are suspected outliers, identify the values. 4

There are two outliers in the data sheet. The values are 5.48 and 5.59. These values are outliers because they are out of the range. 8. (2 points) Use SPSS to make a boxplot or modified boxplot for the variable Sleep_time_week. Copy and paste the graph into this document here . In the space below, explain where the numbers calculated in Question 5 appear. The maximum is the horizontal line at the top of the boxplot. The minimum is the horizontal line at the bottom of the boxplot. The median is the line splitting the rectangle in half in the boxplot. Q1 is in the bottom half of the rectangle around the half point, while Q3 is in the top half of the rectangle around the half point. 9. (2 points) For the variable Sleep_time_week , explain if the mean and standard deviation are appropriate to describe the distribution. If not, what should be used instead? The standard deviation seems appropriate. A large standard deviation would mean a large spread. We also must consider that the standard deviation is affected by any outliers. Since the data is not spread out largely, it would make sense that the standard deviation is not large as well. 5