Department

Psychological & Brain Sci (Psychology)Course Code

L33 Psych 300Professor

NestojkoChapter

3This

**preview**shows half of the first page. to view the full**2 pages of the document.**Chapter 03: Visual Displays of Data

Beware of misleading graphs! Here are some ways graphs can be misleading:

1. Biased Scale Lie

a. Food magazine rating restaurants, but the ones with zero are just the ones that

the magazine reviewers have not been to, this is not an accurate scale

2. Sneaky Sample Lie

a. The people that rate professors on those websites most likely really loved or really

hated the professor

3. Interpolation Lie

a. Assuming that some value between the data points lies on a straight line between

those data points

b. Ex: reporting a drop in crime between two years without looking at the other

years before or afterward

4. Extrapolation Lie

a. Assuming that values beyond the data points will continue indefinitely

5. Inaccurate Values Lie

a. Tells the truth in one part of the data but visually distorts it in another place

b. Truncated Y-Values: when you “zoom in” and make the difference look huge on

bar graphs and in reality it is just .01% or less

Types of Graphs:

● Scatter Plot Graph - a graph that depicts the relation between two scale variables

○ No Relation: looks like a jumble of random dots

○ Linear Relation: the relation between variables is best described by a straight line

○ Nonlinear Relation: the relation between variables is best described by a line that

breaks or curves in some way

● Line Graph - a graph that is used to illustrate the relation between two scale variables

○ Time Plot: a graph that plots a scale variable on the y-axis as it changes over an

increment of time labeled on the x-axis

● Bar Graph - a visual depiction of data in which the independent variable is nominal or

ordinal and the dependent variable is scale

○ Great for highlighting differences in means

○ Independent Variable (X - axis): Nominal or Ordinal

○ Dependent Variable (Y - axis): Scale

■ Describe the data as “(what you are measuring) on the (test name) test”

○ The height of each bar typically represents the average value of the dependent

variable for each category

○ Including a “figure caption” that describes more info about the graph

○ Pareto Chart: a type of bar graph in which the categories along the x-axis are

ordered from highest bar on the left to lowest bar on the right

● Pictorial Graph - a visual depiction of data typically used for an independent variable

with very few levels (categories) and a scale dependent variable

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