Statistics and Research Methods

How to lie, sway, and mislead using statistics

When confronted with any type of data, ask yourself…

o who is included in the sample?► Science – uses random sampling► Pseudoscience – biased selection

o how large is the sample?► Science – >100 if lab, >1K if other ► Pseudoscience – N=1, anecdotal

When confronted with any type of data, ask yourself…

o what data is being presented?► Science – presents all data ► Pseudoscience – only biased

o how is the data presented? ► Science – graphing standards► Pseudoscience – graphs can

lie!

Misleading Graphs

Mean, Median, Mode

1994 Baseball strike about salary:

-Owners argued: typical salary is $1.2 Million

-Players argued: typically salary is $415,000

Which measure of central tendency was each side using?

Mean, Median, and Mode

When confronted with any type of data, ask yourself…

o is this correlation or causation?

► To understand the difference between correlation and causation, we first need to understand how the data is collected…

Research Methods

Correlations

Correlation coefficients range from –1.0 to +1.0

Sign indicates direction ( positive +, or negative - )

Number refers to the strength of the relationship ( higher = stronger )

Experiment

Correlation v. Causation

Depressed Mood Impaired Sleep

Depressed Mood Impaired Sleep

Family Conflict

Depressed Mood Impaired Sleep

Cause?

Cause?

Caus

e?

Cause?

Apply what we have learnedo Quizzes taken from Learning

Module - http://www.psych.ualberta.ca/~ITL/ct/

o Does watching violent TV make children aggressive?o How would you conduct a correlational study

testing this research question? o How would you conduct an experimental study

testing this research questions?

Correlational? or Causational?o A newspaper headline reads, Heavy Drinkers

Get Lower College Grades.

o Your psychology textbook states that some people remember concrete words better than abstract words.

o People who were abused as children are more likely than others to become child abusers

o A health magazine reports that depressed people who continue medication for at least six months are less likely to relapse than people who take medication for less than six months

Horoscope Study

Writing Exercise #2o Horoscope experiment