Interpreting scatterplots
This presentation is the property of its rightful owner.
Sponsored Links
1 / 13

Interpreting Scatterplots PowerPoint PPT Presentation


  • 187 Views
  • Uploaded on
  • Presentation posted in: General

Interpreting Scatterplots. Presentation 2.3. Scatterplots. When looking at scatterplots, we will look for: Association (or direction) Form Strength Outliers. Direction. A trend that runs from the upper left to the lower right is said to have a negative association or direction.

Download Presentation

Interpreting Scatterplots

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Interpreting scatterplots

Interpreting Scatterplots

Presentation 2.3


Scatterplots

Scatterplots

  • When looking at scatterplots, we will look for:

    • Association (or direction)

    • Form

    • Strength

    • Outliers


Direction

Direction

A trend that runs from the upper left to the lower right is said to have a negative association or direction.

A trend running the from the lower left to upper right has a positive association or direction.

It is a lot like slope!


Direction1

Direction

  • It is possible for a scatterplot to have no association or direction.

  • This occurs when the plot looks like a random splattering of dots.


Interpreting scatterplots

Form

  • Form:

    • If there is a straight line (linear) relationship, it will appear as a cloud or swarm of points stretched out in a generally consistent, straight form.

    • If the relationship isn’t straight, but curves, while still increasing or decreasing steadily, we can often find ways to make it more nearly straight.


Strength

Strength

  • Strength:

    • At one extreme, the points appear to follow a single stream (whether straight, curved, or bending all over the place).

    • At the other extreme, the points appear as a vague cloud with no discernable trend or pattern.

  • Note: we will quantify the strength soon (that’s the r).


Outliers

Outliers

  • Outliers:

    • As before, points that do not follow the pattern.

    • Outliers may be in either the x-direction, y-direction, or both directions.

    • There’s no better example than the 2000 presidential election.


Outliers1

Outliers

  • 2000 Presidential Election

    • Remember Florida

    • The scatterplot on the next page details the number of votes for Bush and the number of votes for Buchanon.

    • As you would expect, the more people voting for Bush should mean more people voting for Buchanon (since there are simply more people voting).

    • In Palm Beach County there was much confusion about the ballot.

      • The Democratic Party alleged that the ballot was poorly designed thus skewing the vote.

      • The scatterplot shows the evidence.


2000 presidential election

2000 Presidential Election


2000 presidential election1

2000 Presidential Election

  • Apparently in Palm Beach County only, a disproportionate number of people voted for Buchanon.

    • This point is a great example of an outlier.

      • The outlier is in the y-direction (vertical).

  • Why did this happen?

  • The next slide shows the ballot voters used.


The palm beach county ballot

The Palm Beach County Ballot


Scatterplots1

Scatterplots

  • Remember, when looking at scatterplots, look for:

    • Association (or direction)

    • Form

    • Strength

    • Outliers


Scatterplots2

Scatterplots

  • This concludes this presentation.


  • Login