Explore BrainMass

# Statistics

Not what you're looking for? Search our solutions OR ask your own Custom question.

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

Please see attached file for data required.

PC World provided ratings for 15 notebook PCs (PC World, February, 2000). The Performance Score is a measure of how fast a PC can run a mix of common business applications as compared to a baseline machine. For example, a PC with a performance score of 200 is twice as fast as the baseline machine. A 100-point scale was used to provide an overall rating for each notebook tested in the study. A score in the 90s is exceptional, while one in the 70s is good. The data for 15 notebook PCs are include in the following Chapter 3 dataset: PCs.

1. Write a paragraph describing the dataset. Identify the elements and variables, as well as the sample and population of interest. Identify the scale for each variable. Does the data represent time-series or cross-sectional data? Is it an experimental or observational study?

2. Construct a frequency distribution for the variable 'Performance Score' that includes frequency, relative frequency, and percent frequency. Represent the frequency distribution graphically using a bar graph or pie chart. Categories and percentages should be clearly labeled. You are responsible for determining the number of classes, class limits, and width of each class. Discuss what the frequency distribution tells us about the data.

3. Compute the mean, median, standard deviation, coefficient of variation, skew values, and 85th percentile for both variables included in the study. Which variable contains the most variation? What else do these descriptive statistics tell us about the data?

4. Compute the covariance and correlation coefficient for the relationship between Performance Score and Overall Rating. What does the correlation coefficient tell us about the relation between these two variables? Depict the relationship between the variables graphically using a scatterplot.

5. Assume that Performance Scores are normally distributed. What is the probability that a randomly selected notebook PC would have a performance score above 190? What is the probability that a randomly selected notebook PC would earn a performance score between 142 and 225?