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Midterm

# PSY100Y5 Study Guide - Midterm Guide: Francis Bacon, Observational Error, Psychometrics

Department
Psychology
Course Code
PSY100Y5
Professor
Dax Urbszat
Study Guide
Midterm

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1 LAB TEST PREP
LAB 1 - Measurement and experimental design
Scientific method: is
methodology and philosophy for identifying causation by a variable (x) that results
in a behaviour (y) while holding other variables that might affect behaviour
constant.
Prove that if X causes Y then Y should not happen if X isn’t present
A way to prove causation
Proved through manipulating x twice while measuring y and leaving z constant
X - Independent Variable - The variable manipulated to prove causation
Y - Dependent Variable - The behaviour that is being measured
Z - Controlled Variables - Things we want to keep the same
Psychology:
the scientific study of behaviour
o Why do people behave the way they do? Something is “causing” you to do
something
o Empirical - Perform experiments to prove causation
Sir Francis Bacon:
did empirical testing of scientific study, he also he statistical concept of correlation
and widely promoted regression toward the mean. He was the first to apply
statistical methods to the study of human differences and inheritance of
intelligence. Was really into psychometrics.
Progressive error:
A difference in scores (y) in each manipulation of (x) caused by progressing
Getting better with practice and fatigue effects
Use counterbalancing to control progressive error
Counterbalancing:
Used to control progressive error
Randomizing trials
Random error:
Unexplained differences that exist between a true score and obtained score
Variability in response due to Unknown factors
Averaging:
To control for random error
Measure repeatedly and take average
Good estimate for true scores and behaviour
3 questions:
HOW DOES THE DARTBOARD EXAMPLE DEMONSTRATE PROGRESSIVE
ERROR?
When you throw the darts the first time they are your “practice shots”

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When you blow on your hand and throw the second set of darts, it’s not the blowing
previous attempts/practice trials on throwing the darts
X = The blowing of the hand Y = Better aim
First 4 shots without X - (No Practice)
Second 4 shots with X - (With practice)-Better aim = Progressive error
Use the method of counterbalancing to control progressive error
A.B.B.A (order in which you throw darts with or without blowing on your hand)
HOW DOES THE GOLF BALL EXAMPLE DEMONSTRATE RANDOM ERROR?
-Same person hits multiple golf balls
-They hit as hard as they can every time
-All distances will be different, even under exact same conditions (this is random
error)
-How to control for Random Error: add up distances, divide by # hits to get an average
WHAT IS THE SCIENTIFIC METHOD?
-a way to prove causation by manipulating X twice while measuring Y and leaving Z
constant
-allows us to show how X variable causes change in Y variable
Proves causality (that a change in X variable changes the outcome of another”Y”)
-able to prove that some variable (x) causes people to behave a certain way (outcome-
y) while other variables (z) might affect behaviour that are held constant (ruled out)
- test once when x is there (to cause the behaviour), once when x is not there (to see
that the behaviour does not get caused), WHILE controlling for other relevant causes
(Zs)
EXPERIMENTAL QUESTION
- How COMPREHENSION (X) will affect READING SPEED (words per minute) (Y)
Dependent variable (Y)
- Reading speed (words per minute)
Independent Variable (X)
- With and without the need to comprehend text
CONDITION A
- Low need is ‘RATE HOW INTERESTING
CONDITION B
- High need is “WRITE A SUMMARY SENTENCE
We know that practice also affects reading behaviour as do many other factors (trying
harder, distraction, not being ready) so we need to control for these variables or
minimize them
CONTROL VARIABLES (Zs)
- To control for progressive error à Counterbalancing
- To control for random error à taking averages
8 trials
- 4 A trials (Rate interest)
- 4 B trials (Write Summary sentence)