# Psychology 2820E Midterm: Second Term

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29 Jul 2016
School
Department
Professor
Today
Statistics are tools, not fear-inducing instruments of torture
Some basics of measurements
No previous work in the area, new data, we just want to explore what happens
Tends to be more qualitative
Exploratory
Descriptive
We want to understand cause and effect, it explains something
A lot of quantitative data, but can use qualitative by using open ended questions
Explanatory
Using one piece of information to predict another
Predictive
Data's purpose is…
Data can be quantitative or qualitative
Data's purpose is multiple in nature and it depends on what we are doing with our research question
Statistics
Frequencies, a graphic representation, central tendency, distributions
Describing a sample (the average population age)
Descriptive
Probability of something occurring , where data standards in relation to normal, t-tests, analyses
Inferential
The Language of Statistics and Definitions and Scaling
Saturday, May 28, 2016
8:51 PM
Second Term Page 1
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Probability of something occurring , where data standards in relation to normal, t-tests, analyses
of variance, correlations, regression ,chi-square
The tools we use ( formulas) to make inferences about a population based on our sample
Inference
Experimental statistics, the kind of work in which we want an explanation
Casual inference
Observation comes from a sample, which forms our data
Stats makes us make our data observation inference to make a conclusion
Reasoning from an observation to a conclusion
Population
Everyone in the group of interest
Broad as all adult humans or as narrow as only females between 18-24 that are taking stats
at western
Everyone
Parameters
A population is a complete collection of anything, and a parameter is a numerical characteristic of a
population.
Sample
A sample is a subset of the population; a measurable characteristic of a sample is called a statistic.
Sampling is the process of selecting sample from the population. Random sampling is a method in which
each member of the population has an equal chance of being selected. In stratified random sampling,
the population is divided into relevant groups (strata), and then random samples are taken from each
group.
Generalizations
Statistics
The representative group --> the individuals within that population that you are subjecting to your
testing procedure
If it isn't representative you are lacking external validity
Must be a valid representation of the population
Representative sampling = external validity
Random sampling
Availability sampling (convenience sampling)
Experimental Study
You manipulate in order to cause an effect
Manipulation study
A variable is anything that may take on different values or amounts.
The independent variable in an experiment is the variable manipulated and controlled by the
experimenter to determine it effect on the dependent variable. In the behavioral sciences, the dependent
variable is the measurement of behavior.
Levels --> minimum of two levels
This is the variable you are manipulating
Independent variable(s)
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This is the variable you are manipulating
The variable that is being measure
This is where we can see the effect
Dependent Variable(s)
The goal is…
To make analytical comparisons
Measurement error (tool, malfunction)
Researcher error
Participant error - reaction time is slower from being up the night before, etc
Error is about variability that we can't account for based on our manipulation
Any differences not accounted for by manipulation
E.g., intelligence differences, speed differences, sex differences, personality
Differences in the dependent variable between groups
Statistically this is reduced to…
The smaller the error, the greater the ratio
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Non-Experimental Study
Relationships that are predictable
Variables in a world of mediators and moderators
The goal is…
To find associations and predictors
Statistically this is reduced to…
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What we're going to learn
The language of statistics
How we approach statistics
We then have the ability to look at a research question and know if you should be using a T-
test or an Anova
Which is the rationale for the statistics used
By explaining the theory
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