Observational units response variable type

Info icon This preview shows pages 355–358. Sign up to view the full content.

Observational units: Response variable: Type:
Image of page 355

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Chance/Rossman, 2015 ISCAM III Investigation 5.6 355 (b) Open the CatJumping.txt data file and produce numerical and graphical summaries of the takeoff velocity variable. Describe the distribution of takeoff velocities in this sample (shape, center, variability, unusual observations). (c) Based on your analysis in (b), if you were going to randomly select a domestic cat, what is your best prediction of its takeoff velocity? (d) Do you think there will be a relationship between a cat’s take off velocity and its body mass? If so, do you think heavier cats will tend to have larger or smaller takeoff velocities than lighter cats? We will need a new graphical summary to visually explore the relationship between two quantitative variables, the scatterplot . Technology Detour Scatterplots In R > plot(bodymass, velocity) or > plot(velocity~bodymass) > scatterplot(bodymass, velocity) the scatterplot function is in the package car In Minitab x Choose Graph > Scatterplot , with the Simple option. Click OK . x Double click on velocity to enter this as the Y variable and then double click on bodymass to enter this as the X variable. x Click OK . x [Or type MTB> plot 'velocity'*'bodymass' ] (e) Describe the relationship between a cat’s takeoff velocity and its body mass, as displayed in this scatterplot. Does this pattern confirm your expectation in (d)?
Image of page 356
Chance/Rossman, 2015 ISCAM III Investigation 5.6 356 (f) Do any of these cats appear to be outliers in the sense that its pair of values (body mass, takeoff velocity) does not fit the pattern of the majority of cats? If so, identify the ID for that cat and describe what’s different about this cat (in context). Terminology Detour Scatterplots are useful for displaying the relationship between two quantitative variables. If one variable has been defined as the response variable and the other as the explanatory variable, we will put the response variable on the vertical axis and the explanatory variable along the horizontal axis. In describing scatterplots you will describe the overall pattern between the two variables focusing primarily on three things: x Direction : Is there a positive association (small values of y tend to occur with small values of x and large values of y tend to occur with large values of x ) or a negative association (small values of y tend to occur at large values of x and vice versa)? x Linearity : Is the overall pattern in the scatterplot linear or not? x Strength : How closely are the observations following the observed pattern? The above scatterplot reveals a fairly strong, negative association between body mass and takeoff velocity, meaning that heavier cats tend to have a smaller takeoff velocity than larger cats. The relationship is somewhat linear but has a bit of a curved pattern. There is one outlier cat (cat C) with a very high takeoff velocity despite having a very large body mass.
Image of page 357

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Image of page 358
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern