r.g. bias | [email protected] | name that tune. song title? performer(s)? 1
TRANSCRIPT
R.G. Bias | [email protected] |
First . . .
Reaction to a mid-course class evaluation.– Just 8 respondents.– Mostly positive.– One answer that troubled me:
Course objectives and assignments are clearly stated.
25% (2) 50% (4) 12.5% (1) 12.5% (1) 0% (0)
Level-setting. Where are we and where are we headed?
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R.G. Bias | [email protected] |
ObjectivesAfter this class (or these 3 weeks of classes) you
will (it is my hope!): know something about how scientists
(information scientists) gather new information. AND you’ll be good at evaluating information
others offer you. I want to arm you with a scientist’s skepticism,
and a scientist’s tools to conduct research and evaluate others’ research.
- Randolph – remember to take roll.
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There are three kinds of lies: lies, damned lies, and statistics.– Benjamin Disraeli (1804 – 1881), British
politician
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Statistics are like a bikini. What they reveal is suggestive, but what they conceal is vital. – Aaron Levenstein, U.S. politician
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The statistics on sanity are that one out of every four Americans is suffering from some form of mental illness. Think of your three best friends. If they're okay, then it's you. – Rita Mae Brown, U.S. author
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First . . .
There are two components of this and any class: Instruction and Evaluation.
Let’s get the evaluation out of the way, early.
Need one volunteer.
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“Research shows . . .”
Finger length is a good (and quick!) indicator of intelligence.
One volunteer – measure your finger length in cm. However.
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Hmmmm . . .
Everyone in the class will get a grade of “C”
But still, we can continue with the “instruction” part of the course.
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Oh, so maybe . . .
Just THIS person isn’t too smart. Or maybe finger length is NOT a
good indicator of intelligence.
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Now, an experiment
I will hand you each a slip of paper. Please read it an do NOT let anyone else read it.– Women receive a white slip of paper.– Men receive a green slip of paper.
After everyone has read his/her slip of paper and refolded it, I’ll show some letters of the alphabet, one at a time, for one second each.
After the last one, I’ll say “Go,” and ask you to write down the letters, in order.
Any questions?
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Exp. 1 -- Data
All correct Not all correct
Total
Men 7 (47%) 8 15
Women 3 (13%) 20 23
Total
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Who among you . . .
. . . is a statistical wizard? . . . has experience conducting
research?
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Many ways to learn new things
Method of Authority– trusted authority tells you something
Method of Reason – follow basic logical laws from philosophy
Modeling Trial-and-error Intuition Scientific Method
– belief on the basis of experience
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Three Paths to “Belief”
1 – Naïve acceptance.2 – Cynicism.3 – Critical skepticism.
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What you’ll learn the next 3 weeks
Reliability. (“Oh, just measure it however.”)
Validity. (Finger length a good indicator of intelligence?)
Sampling – picking a representative sample and then generalizing to a larger population
Why larger samples are better
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What you’ll learn (cont’d.):
How to represent a group of numbers, meaningfully. – Frequency distributions– Measures of central tendency– Measures of dispersion (spread)– Graphs/Tables
Operationalizing variables (“intelligence”) Probability Correlation
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What you’ll learn (cont’d.):
Different measurement scales What makes a good research
question? Experimental design
– Independent and dependent variables– Controls, counterbalancing, and
confounds– Hypothesis testing– Inferential statistics (is THAT number
really bigger than THIS number?)
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More than anything else . . .
. . . scientists are skeptical. “Scientific skepticism is a gullible
public’s defense against charlatans and others who would sell them ineffective medicines and cures, impossible schemes to get rich, and supernatural explanations for natural phenomena.”
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Research Methods
Researchers are . . .- like detectives – gather evidence,
develop a theory.- like judges – decide if evidence meets
scientific standards.- like juries – decide if evidence is
“beyond a reasonable doubt.”
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Science . . .
. . . Is a cumulative affair. Current research builds on previous research.
The Scientific Method:– is empirical (acquires new knowledge
via direct observation and experimentation)
– entails systematic, controlled observations.
– is unbiased, objective.– entails operational definitions.– is valid, reliable, testable, critical,
skeptical.
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CONTROL
. . . is the essential ingredient of science, distinguishing it from nonscientific procedures.
The scientist, the experimenter, manipulates the Independent Variable (IV – “treatment – at least two levels – “experimental and control conditions”) and controls other variables.
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More control
After manipulating the IV (because the experimenter is independent – he/she decides what to do) . . .
He/she measures the effect on the Dependent Variable (what is measured – it depends on the IV).
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Key Distinction
IV vs. Individual Differences variable The scientist MANIPULATES an IV,
but SELECTS an Individual Differences variable (or “subject” variable).
Can’t manipulate a subject variable. – “Select a sample. Have half of ‘em get
a divorce.” Consider an Individual Difference, or
Subject Variable, as a TYPE of IV.
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Operational Definitions
Explains a concept solely in terms of the operations used to produce and measure it.– Bad: “Smart people.”– Good: “People with an IQ over 120.”– Bad: “People with long index fingers.”– Good: “People with index fingers at least 7.2
cm.”– Bad: Ugly guys.– Good: “Guys rated as ‘ugly’ by at least 50% of
the respondents.”
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Validity and Reliability
Validity: the “truthfulness” of a measure. Are you really measuring what you claim to measure? “The validity of a measure . . . the extent that people do as well on it as they do on independent measures that are presumed to measure the same concept.”
Reliability: a measure’s consistency. A measure can be reliable without being
valid, but not vice versa.
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Theory and Hypothesis
Theory: a logically organized set of propositions (claims, statements, assertions) that serves to define events (concepts), describe relationships among these events, and explain their occurrence.– Theories organize our knowledge and guide
our research
Hypothesis: A tentative explanation.– A scientific hypothesis is TESTABLE.
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Goals of Scientific Method Description
– Nomothetic approach – establish broad generalizations and general laws that apply to a diverse population
– Versus idiographic approach – interested in the individual, their uniqueness (e.g., case studies)
Prediction– Correlational study – when scores on one variable can
be used to predict scores on a second variable. (Doesn’t necessarily tell you “why.”)
Understanding – con’t. on next page Creating change
– Applied research
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Understanding
Three important conditions for making a causal inference:– Covariation of events. (IV changes, and
the DV changes.)– A time-order relationship. (First the
scientist changes the IV – then there’s a change in the DV.)
– The elimination of plausible alternative causes.
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Confounding When two potentially effective IVs are allowed to
covary simultaneously.
– Poor control!
Men, overall, did a better job of remembering the 12 “random” letters. But the men had received a different “clue.”
So GENDER (what type of IV? A SUBJECT variable, or indiv. differences variable) was CONFOUNDED with “type of clue” (an IV).
R.G. Bias | [email protected] |
Going forward . . .
Annotated bibliography due 3/24 (this Wednesday – same drill, hard-copy in class, digital copy to your TA).
Read those two books that are on reserve in the library – To know a fly and How to lie with statistics.
See you Wednesday.
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