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Research Methods

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Kristie Stevens

on 1 October 2018

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Transcript of Research Methods

The Scientific Method
Different Approaches
case study
Descriptive Statistics
Measures of Central Tendency
Inferential Statistics
Research Methods
operational definition
Sleep boosts memory!
When people are sleep deprived, they have a harder time remembering the previous day's learning.
sleep deprived?
made easier (and more accurate) by operational definitions!
naturalistic observation
Phineas Gage
Kitty Genovese
David Reimer
Anna O
in depth research on a SINGLE subject for revealing important general information
taking stock of important facts, environmental factors, and specific behaviors
10 men, 10 women take a survey; survey should reveal the general attitudes of the whole group and specific differences between groups
all possible units--so in the case of a survey, people!
CHS Student Body
a subsection of the total population that accurately represents the diversity of the population
members from all 4 classes, both genders, and different activities
Surveying without random sampling can produce skewed results!
looking at natural behaviors in the real world
can validate other experimental findings
may study topics that are unethical (at least in a lab)
Things like surveys and naturalistic observation often show us that one trait or behavior may be related to another.
the HIGHER the mileage, the LOWER the value
the HIGHER your rate of accidents, the HIGHER your insurance cost
The less sexual content teenagers see on TV, the less likely they are to engage in sex.
The more income rose among a sample of poor families, the lesser the incidence of mental illness among their children.
POSITIVE= rising and falling TOGETHER
NEGATIVE= rising and falling OPPOSITELY
correlational coefficient of -1
correlational coefficient of +1
Just remember that correlation DOES NOT equal causation! Illusory correlations happen all the time.
A football fan believes that every time he wears a specific jersey his team wins, so each time they play, he will only wear that jersey.
A child makes a record amount of goals in a soccer game when wearing his red socks, so he continues to wear his red socks for each future game, believing that the socks are related to his play.
A student fails an exam given on a Monday so he determines that he is unlucky and unable to pass a test if it is administered on future Mondays.

enable a researcher to focus on the possible effects of one or more factors by manipulating some factors and controlling others
random assignment
double-blind procedure
placebo effect
makes experimental groups equivalent and protects the integrity of the experiment
eliminates bias in research results (think drug research; if patients and researchers alike do not know which drug is being administered, the results will have more integrity)
belief that an inert substance is creating positive results
experimental group
control group
independent variable
dependent variable
group exposed to one version of the independent variable
If we're looking at whether breast-fed babies are more intelligent than those not breast-fed, our breast-fed babies would be the experimental group.
provides the basis of comparison
In our previous example, formula-fed babies.
breast milk
the factor being manipulated
the outcome factor
how intelligent the experimental group is v. the control group
descriptive research
How do you interpret the results?
Measures of Variance
standard deviation
external validity: does it reflect what would happen in the real world?
internal validity: do we know what caused the results of the study?
i.e. naturalistic observations
5 36 36 97 120 247 509
the average measure of how data are distributed; add up and divide the total by how many data points there are
5 36 36 97 120 247 509
the middle score--half should be above, half should be below!
shows up most frequently
5 36 36 97 120 247 509
how much numerical ground is being covered
5 36 36 97 120 247 509
Work out the Mean (the simple average of the numbers)
Then for each number: subtract the Mean and square the result.
Then work out the mean of those squared differences.
Take the square root of that and we are done!
5 36 36 97 120 247 509
12, 996
12, 966
mean= 27,002.3
standard deviation=164.3
a number used to tell how measurements for a group are spread out from the average (mean), or expected value
low standard deviation means that most of the numbers are very close to the average; high standard deviation means that the numbers are spread out.
skewed distribution
examines the lack of symmetry in scores around the average
Normal Curve
even distribution on both sides of the mean
how can you use your data to generalize or know if something is true?
You can conceptualize this visually using a histogram:
Sometimes affected by CONFOUNDING VARIABLES, or variables you cannot control!
You can use standard deviation to compare scores from different distributions using "z scores."
If Clarence scored a 72 on a test with a mean of 80 and a standard deviation of 8, his z score would be -1.
If Maria scored an 84 on the same test, her z score would be +.5
simplifies interpreting their performance results
I don't measure the diameter of individual nails measured at a nail factory--instead, I measure a representative sample and I can make a generalization about the whole population.
Statistics also help us determine if differences (particularly in experiments) occur by chance:
I'm testing the effects of sugar on short term memory.
experimental group:
control group:
can remember 7/15 nouns
can remember 6.9/15 nouns
That's not a big difference!
such a tiny difference that it's difficult to say whether the results occurred thanks to the independent variable or by chance
lots of tests to determine the percentage ( or p score) that indicates whether a result occurred by chance or not--the smaller the p score, the more significant the results. Cut off is p=.05 or a 5% probability results occurred by chance. If the p score is higher, your results are not significant!
But what about experimental ethics?
Take a look at your Stanford Prison Experiment handout.
What potential ethical (related to moral right and wrong) issues do you see?
informed consent
right to withdraw
protection from harm
do you know what you're getting in to?
are they only withholding what's necessary?
can you get out of it if you want to?
are you protected from physical or psychological suffering?
is it certain that you're not going to be exposed when data is released?
does the experiment respect your privacy?
take the mean, subtract it from the score, divide by the unit of standard deviation
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