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Frequency Distribution
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A record of the frequence of scores located in each response category of what's being measured
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Interval Scale
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Ordered equidistant categories having an infinite # of intermediate values and an arbitrary zero point
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Correlation Method
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Observing the naturally occuring relationship b/w two or more variables (as one variable changes, how does the other change?) ex: shoe size and height
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Construct
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Hypothetical concepts (abstract ideas)
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Experimental Method
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Cause and effect relationship; requires manipulation of at least one variable & measuring another variable
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Hypothesis
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Specific testable prediction about the relationship b/w 2 or more variables.
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Nominal Scale (Categorical)
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Category with different names. No quantitative distinctions; numbers may serve as labels
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Ordinal Scale (ordered)
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Category names (or #'s) are represented in an ordered sequence of magnitude; numbers have very limited quantitative properties
ex: attractiveness, job performance
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Ratio Scale
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Interval scale with an absolute zero point (absence of construct) ex: Kelvin, time
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Cumulative Frequency
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Add the frequency at and below each score.
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Scientific Method
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1. Describe the question/problem.
2. Design study->collect data.
3. Analyze data, draw conclusions.
4. Revise theories.
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Operational definition
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Defining a construct by the manner in which the variable is used and measured.
ex: What does intelligence look like (IQ)
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Key elements in any distribution
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1. Set of possible scores
2. The frequency of scores at each category
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Variable
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characteristic that changes or is different from one individual to the next (something that is measured)
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Grouping Guidelines
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1. Have about 10 intervals
2. Interval widths must be equals
3. Use simple numbers for interval widths
4. The lower limit of the interval should be a multiple of the interval widths (ex: 2,4,5,10)
5. Highest &/or lowest interval should not have a zero frequency
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Experimental Group
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Receives the treatment level of the Ind. Var.
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Apparent Limit
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The actual limits of each interval (w/ gaps)
ex: 6.5-6.9
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Real (Exact) Limit
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Limits of the entire interval (closing the gaps)
-always represented with one more place past the decimal that the apparent limit
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Confounding Variable
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Uncontrolled variable that can systematically vary with the ind. var.
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Midpoint
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In the exact middle of the interval
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Quasi-Experiment
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Nonmanipulated Ind. Var.
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Random Assignment
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For each participant, equal chance for assignment to each condition (Holds extraneous variables constant)
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Statistics
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A set of methods and rules for organizing summarizing and interpreting information.
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Control Group
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Does not receive the treatment level of the Ind. Var.;gets treatment or gets placebo treatment
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Independant Variable
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The variable that is manipulated (or controlled)
ex: different groups; positive vs. negative words
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Dependent Variable
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The variable that is observed/measured.
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Inferential Statistic
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Procedures used to generalize the characteristic of a sample of a population (Infer to the population)
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Theory
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Integrated set of principles that explain all the facts and predicts observed events.
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Qualitative Difference
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Change in kind/quality ex: eye color, different drugs
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Continuous Variable
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Variable with an infinite # of possible intermediate values b/w any two values, qualitative differences.
ex: time, distance, weight
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Quantitative Difference
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Change of amount
ex: different amounts of drugs
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Discrete Variable
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A)Represents seperate categories for each level of the variable with no intermediate values
B) Qualitative differences
ex:gender, # of students
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Parameter
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Numerical value that describes a characteristic of a population.
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Population
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Set of individual of interest in a particular study.
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Random Sampling
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Process of obtaining a sample that requires every individual in the population has equal chance of selection (representatives of whole population)
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Statistic
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Numerical value that describes a characteristic of a sample
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Sample
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Set of individuals selected from a population who are intended to represent the population in research study.
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Sampling Error
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The numeric difference that usually exists b/w the sample statistic & population parameter ex) voting prediction, (aka: margin of error)
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Descriptive Statistics
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Procedures used to summarize, organize, and simplify data (describe)
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