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Are you a student at risk?

• The first tutorial quiz has been available on webCT since this Monday morning

• 14 questions, unlimited attempts, worth marks in this course, closes this Sunday

• Have you done it?• If not, why not?

• Information on the quizzes, manual p.11-12• Find the actual quiz on webCT: Assessment>

Tutorial Quizzes

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http://www.dailymail.co.uk/news/article-395568/Dont-rely-homeopathy-beat-malaria-doctors-warn.html

10/10 Homeopaths prescribe homeopathic protection for malaria! (UK newspaper studies)

http://www.senseaboutscience.org.uk/index.php/site/project/71/

http://news.bbc.co.uk/1/hi/uk/5178488.stm

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Science and StatisticsLecture 2

The power of a name: The power of a name: Measurement and constructsMeasurement and constructs

Dr Caleb Owenscaleb.owens@sydney.edu.auConsultation: Wednesdays 9-10am

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What is the difference between science and technology?

• Technology is a craft

• Science is an understanding

• Is technology just ‘applied science’ ?

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Scientific constructs and concepts

• Energy– Heat energy– Kinetic energy– Work

• Structures– atom– molecule– bonds / forces

• Process– Reaction– Conduction– Gravity– Time

• Life – Ecosystem– Food chain– DNA– cell

•Approximations of reality

•Descriptions of reality

•Concepts we try to measure

•Concepts we use to make predictions

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Some psychological concepts and constructs

• Memory• Intelligence• Personality• Consciousness / Self-control• Attitude• Mood• Arousal• Motivation

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Variables• Anything that varies.

– The opposite of a variable is a constant

• It depends on the experimental context– Is ‘sex’ a variable in an all female study on

body image?– Is ‘sex’ a variable in a study of differences

between the map reading ability of males and females?

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Independent & Dependent Variables

• Presumed Cause• Antecedent Cause• Stimulus Variable

• Behaviour of Interest• Response Variable

IndependentVariable

DependentVariable

Manipulated byexperimenter

Measured byexperimenter

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• Independent variables are manipulated by an experimenter

• Dependent variables are measured by an experimenter

• Extraneous variables are controlled by an experimenter (kept constant) or allowed to vary randomly

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Independent & Dependent Variables

• Is children’s intelligence affected by watching television?

• Does marijuana use lead to schizophrenia?

• Is there a relationship between your personality and your health?

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Defining Variables

• Conceptual Definitions:– Define variables in terms of other concepts

• E.g. “Stress: a state of strain, whether physical or psychological”

– Sometimes called constructs– Are they real/reliable? (reification)

– Theoretical constructs are unobservable, so how can we measure them? (operational definition)

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Reification

• The treatment of an analytic or abstract relationship as though it were a concrete entity

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“Natural”• Robert T Carroll on “natural” (from: http://www.skepdic.com/natural.html)

– Something present in or produced by nature is natural, such as an earthquake or typhoon, or a poisonous mushroom.

– Just because something is natural does not mean that it is good, safe or healthy. Herbs are natural but they are also drugs when used in the diagnosis, treatment, or prevention of a disease. The chemicals which comprise synthetic drugs are natural. St. John's Wort (Hypericum perforatum) is natural, but it is a drug. Why do some people say that they prefer St. John's Wort to drugs for depression? If someone said that he preferred Irish whiskey to alcohol, we'd think he was confused.

• Other terms that we assume have a specific meaning: organic, free range, dolphin friendly, chemical free, anti-oxidant – Choice magazine and the ACC often review the commercial use

of such terms

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Luck

• When good or bad things happen to us in a pattern we say we are ‘lucky’ or ‘unlucky’– As an adjective this is fine

• However some people believe luck is a thing or a cause, not merely a result (or a description of how things have turned out)

• Psychologists study people’s “understanding of luck” as a factor in gambling behaviour, but ‘luck’ as a superstitious concept is not studied.

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“Vitalistic” thinking• Common in young children:

– “mountains are for climbing”– “lions are for walking around and being in

zoos”

• Some adults think this way– e.g. “When we have a cut finger what makes it

get better?”• Our cut finger uses energy to get better / our cut

finger wants to get better• Finger tissue and veins start growing / the wound

is purified of destroyed cells

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“Energy” :

• Vitalistic: Healing, living, purifying, dying, growing, withering, hereditary, in motion, poisonous, an emotion, good, bad, masculine and feminine

• Scientific: Energy can manifest itself as heat, energy can be a physical capacity for doing work

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Adults who use “vitalistic thinking” are more likely to believe in:

• Paranormal agents• Ghosts• Spirits• God• Luck• Telepathy• Spiritualism• Precognition• lunar effects• Amulets• crystal power• Witches• astrology

• Chiropractic• Acupuncture• Homeopathy• Natural remedies• Megadoses of vitamins• Magnetic field treatments• Kirilian photography• Stone therapy• Reiki• reflexology

Lindeman & Saher (2007) British Journal of Psychology, 98, 33-44.

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Vitalism around the world

• China : CHI / QI• Japan : Ki• Indian : PRANA• Western Europe (Homeopathy) : SUBTLE ENERGY• Western Europe: ANIMAL SPIRITS*

• The flow of animal spirits carried our thoughts– *But after 1857 vitalism begins to disappear in the West

• These metaphysical concepts are the “fairies in my backyard”. Can they ever be measured?

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“Ki” master video

• A Japanese Ki master believes he can knock out people only with the power of ki

• He is seen knocking out an entire room full of his disciples (who no doubt know what is expected of them)

• He put’s an advertisement online for a $5000 reward for anyone who can beat him with tragic consequences

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The pragmatic fallacy

• “Something is true because (something else) works!” – i.e. an explanation or model for how an effect might happen is also right just because the effect is proven– e.g. Chi is real because acupuncture works

• These are two separate questions:– Does acupuncture work? Why does it work?

• In psychology we know about many effects, but are not always sure of the explanation, theory or model behind these effects– A good start is to use constructs which are useful, real

and easily defined

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Evidence

e.g. Acupuncture works!

Theory

e.g. A invisible force call Chi flows through our bodies and must be unblocked

Theory 2

e.g. The needles excite the parasympathetic nervous system

Theory 3e.g. The placebo effect causes peace of mind

Eliminate theories which use unfalsifiable concepts

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Evidence

e.g. Psychotherapy works!

Theory

e.g. Talking about your childhood unshackles the unconsciousness and allows unfulfilled wishes to gain expression

Theory 2

e.g. Talking per se to a sympathetic human makes you feel better!

Theory 3e.g. Cognitive behavioural therapy give you skills and techniques to cope

Eliminate theories which use unfalsifiable concepts

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Psychological concepts and constructs

• Memory• Intelligence• Personality• Consciousness / Self-

control• Attitude• Mood• Arousal• Motivation

• Notice how most cannot be directly observed

• Where do they come from?

• Are they useful?• How do we define

them?

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Defining Variables

• Operational Definitions:– Define in terms of the operations carried out

in measuring or manipulating them• E.g. we might measure motivation in a rat by

looking at its rate of button pressing

– An objective procedure that others can replicate (for IVs and DVs).

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Operationalising ConstructsConstruct:

(Comes from theory)

Operational Definition:

(Can be observed)

Motivation Rate of button pressing

Memory Number of things recalled

Learning Decrease in time to solve puzzle

Personality Score on questionnaire

Arousal Heart rate, blood pressure

Attitude Number circled on a scale

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Two warnings about Operational Definitions

• Don’t confuse the operational definition with the construct– E.g. Intelligence is what intelligence tests

measure.

• The operational definition might be a good or a bad way to observe the construct– E.g. Is circling a number on a scale a good way

to observe a person’s attitude?– Controversy over self-report as a measure of

personality and attitude (e.g. prejudice)

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Categorical vs. Continuous

• Categorical variables:– Sometimes called qualitative– Values of the variable fall into discrete classes

(e.g. gender, favourite colour, country of birth)

• Continuous variables:– Sometimes called quantitative or scale– Values of the variable can be anywhere within

a range (e.g. age, weight, height, speed of driving)

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Scales of Measurement

• The categorical / continuous distinction can be broken down further into scale types

Categorical (Qualitative)

Continuous (Quantitative)

Scales Nominal Ordinal Interval Ratio

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Nominal Scales

• Used for categorical (not continuous) data

• Numbers are arbitrary – they act as labels, they are there instead of names (nominal)

• Numbers indicate:– sameness or difference

• Numbers don’t indicate size or order

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Nominal Scales

Scale 1 Scale 2

Asian = 1 Hispanic = 7

Hispanic = 2 Caucasian = 1

Aboriginal = 3 Asian = 17

Caucasian = 4 Aboriginal = 42

Other = 5 Other = 45

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Ordinal Scales

• Used where numbers are ranked / ordered• Numbers indicate:

– Sameness or Difference &– More or less

• Numbers don’t tell us anything more than order– E.g. the difference between Titanic revenue and

Return of the King revenue, may be much greater than the difference between return of the King Revenue and the gross for Dead Man’s chest

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Ordinal Scales

Name: World box office rank:

Avatar 1

Titanic 2

Return of the King 3

Dead Man’s Chest 4

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Interval Scales

• Used where numbers are separated by equal-sized intervals but have no meaningful or absolute zero.

• Numbers indicate:– Sameness or difference &– More or less &– Same or different intervals, greater or smaller

intervals

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Interval Scales

Temperature (ºC)

0º

10º

15º

20º

100º

Temp.

Difference

10º

5º

5º

80º

Order on differences

10º > 5º

5º = 5º

80º > 5º

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The ‘taller than Tom’ scale

• 0 = same height as Tom Cruise

• 1 = 1cm taller

• The difference in TTT between Hugo and George, and George and Katie, is the same (10)

• BUT George is not ‘twice as tall’ as Katie, and Hugo is not three times as tall as Katie

Name: TTT:

Hugo 30

Katie 10

George 20

Gimli 0

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Interval Scales

Name: Amount more than Harry Potter #1:

Avatar $1,637,296,346

Titanic $866,642,109

Return of the King $160,561,361

Dead Man’s Chest $91,674,737

Harry Potter and the Sorcerer’s Stone took $968,657,891

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Ratio Scale

• Numbers indicate:– Sameness or difference &– More or less &– Same or different intervals, greater or smaller

intervals– Ratios, fractions

• Ratio Scales have an absolute zero point

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Ratio Scales

• Examples: Time, length, weight, money

– 2km + 7.3km = 9.3km– 100 kg is twice as heavy as 50 kg– A $0 balance means you have no money! (but

0ºC does not mean there is no energy)

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Ratio Scales

Name: World box office takings:

Avatar $2,605,954,237

Titanic $1,835,300,000

Return of the King $1,129,219,252

Dead Man’s Chest $1,060,332,628

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Summary

• Science is distinguished from technology by an understanding of the underlying mechanisms and processes

• Be cautious when dealing with concepts– Are they real ‘things’– Are they just adjectives or properties?– Can they be defined in a useful way?

• The thing you measure does NOT equal the concept you want to talk about– (The thing you measure can only, at best, reflect or

approximate the thing you want to talk about)• The kind of scale you use in research can limit the

inferences you can draw

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Don’t forget wikipedia for more!

From

wikipedia:

http://en.wikipedia.org/w

iki/Ratio_scale#R

atio_measurem

ent