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Statistic Exam 1
Vocab
38
Other
Graduate
10/14/2009

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Term
Variable
Definition
characteristic which can take on different values in different circumstances
Term
Random Variable
Definition
a functional association of a real number with each elementary event in a defined sample space. A statistical concept that is more of a process
Term
Measurement
Definition
process of association of numbers with observations
Term
Sample
Definition
subset of a population
Term
Population
Definition
a set of possible values
Term
Parameter
Definition
a characteristic of population
Term
Statistic
Definition
a characteristic of a sample. measure of only a sample
Term
Random Sample
Definition
Each element of the population has equivalent probability of entering into the sample
Term
Discrete Random Variable
Definition
finite number or limit on possible set of answers
Term
Representative Sample
Definition
sample chosen represents larger population
Term
Indenpendent Variable
Definition
Manipulated variable (predictor) explanation of the variance in the DV
Term
Dependent Variable
Definition
outcome variable (predicted)
Term
Extraneous Variable
Definition
anything else besides variables examined and are independent and not measured
Term
Confounding Variable
Definition
a potentially influencing extraneous variable that varies systematically with the independent variable. A kind of systematic error. Cannot assume causality when confound is present
Term
Error
Definition
Variations in data oproduced extraneous variables. Not a mistake
Term
Systematic Error
Definition
introduced by influencing variable, perhaps associated with lack of validity on an individual subject/case basis. Canbe viewed as a type of bias
Term
Randomized Error
Definition
Related to lack of precision and lack of reliability
Term
Nominal Scale
Definition
Categories, groupings. No specific order. I.e. ethnicity, gender
Term
Ordinal Scale
Definition
measurement scale for values that can be assigned a greater than or less than value. A ranking system. Cannot determine degree to which one is better than the next.
Term
Interval Scale
Definition
difference between values on the scale has the same meaning. scores can be added or subtracted and has a mean as a representative measure of central tendency. No zero point, or one is assigned.
Term
Ratio Scale
Definition
an interval scale with an absolute zero. Scale must be unipolar (only positive values, negative meaningless) or bipolar (both positive and negative values are meaningful) and can be continuous or discrete
Term
Manifest Variable
Definition
observed. often used to measure a latent variable
Term
Latent Variable
Definition
intervening or underlying variable that cannot be measured
Term
Reliability
Definition
repeatability or consistence in repetition.
Term
Content Validity
Definition
the scale measures the material it was designed to measure (its content area)covers most of the content area
Term
Criterion Validity
Definition
reflects the success of measures used to prediction and estimation. Two types: concurrent and predictive
Term
Concurrent Validity
Definition
measures the degree to which a test correlates with another test designed to measure a similar outcome
Term
Predictive Validity
Definition
the degree to which the measure can predict some construct..gre's
Term
Construct Validity
Definition
emprical and theoretical support for the interpretation of the constructs
Term
Internal Validity
Definition
cleanness of outcome... can we say that X causes Y
Term
External Validity
Definition
generalizability of a causal relationship
Term
Bernoulli Theorem
Definition
the larger the N, the closer the X should be to p(x)
Term
Bernoulli Process
Definition
experiment or process that can only result in one of two outcomes. with replacement
Term
Unbiased
Definition
mean of sampling distribution equals population paramenter being estimated
Term
Consistent
Definition
with larger sample sizes, the likelihood that an observed statistic deviates much from a population parameter goes down. Essentially the law of large numbers. With larger sample sizes, statistics become better estimaters.
Term
Efficient
Definition
if looking at two statistics of a sampling distribution (mean or median), the more efficient estimator will have the smaller sampling variance and smaller error (when estimating a population parameter)
Term
Sufficient
Definition
meu and sigma are sufficient estimaters for normal distributions. Statistics that we can estimate distribution from.
Term
Central Limit Theorem
Definition
as N increases, sigma squared and x bar approaches meu, the sampling distribution of the mean approaches normality as N gets large. Occurs regardless of shape of original distribution
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