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statistics
statistics
28
Psychology
Graduate
06/16/2011

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Term
an interval scale
Definition
he distance between any two adjacents units of measurement is the same but the zero point is arbitrary. eg. temperature 30 degrees more than 40 degrees
ie. heights of tides, and the measurement of longitude.
Term
ratio scale
Definition
have equal intervals and an absolute zero. e.g. scores on a 100-point test would all be examples of ratio scales. I
Term
Central Tendency
Definition
Indicates where the distribution is on a line
Term
Spread/Dispersion/Variability
Definition
Indicates how the scores are around the central point. he data values in a sample are not all the same. This variation between values is called dispersion.

When the dispersion is large, the values are widely scattered; when it is small they are tightly clustered
Term
Positive skew
Definition
long tail on right
skewness is more common
Term
negative skew
Definition
long tail on left
Term
Peakedness/Kurtosis
Definition
Describes how peaked or flat the distribution is
Term
platkurtic
Definition
relatively flat
Term
mesokurtic
Definition
mid level height
Term
leptokurtic
Definition
relatively peaked
Term
descriptive statistics
Definition
you are simply describing what is or what the data shows
Term
multiple regression
Definition
The purpose is to learn about the relationship between several independent or predicts variables and a dependent or criterion variable.
is to analyze the relationship between several independent or predictor variables and a dependent or criterion variable.
aim is to find a linear relationship between a response variable and several possible predictor variables.
Term
factor analysis
Definition
a technique for identifying groups or clusters of variables.
used to
(1) to reduce the number of variables and
(2) to detect structure in the relationships between variables, that is to classify variables.
Therefore it is applied as a data reduction or structure detection method

For example, suppose we want to measure people's satisfaction with their lives. We design a satisfaction questionnaire with various items; among other things we ask our subjects how satisfied they are with their hobbies (item 1) and how intensely they are pursuing a hobby (item 2). Most likely, the responses to the two items are highly correlated with each other. Given a high correlation between the two items, we can conclude that they are quite redundant.
Term
ANOVA
Analysis of Variance
Definition
purpose is to determine whether a significant difference exists between more than two group means.
procedure employs the statistic (F) to test the statistical significance of the differences among the obtained MEANS of two or more random samples from a given population.
Term
f test
Definition
value provides a test for the statistical significance of the observed differences among the means of two or more random samples.
The test employs the statistic to test various statistical hypotheses about the mean (or means) of the distributions from which a sample or a set of samples have been drawn.
Term
chi square
Definition
is the relationship between two categorical variables

Rather than measuring the value of each of a set of items, a calculated value it compares the frequencies of various kinds (or categories) of items in a random sample to the frequencies that are expected if the population frequencies are as hypothesized by the investigator.
used to assess the "goodness of fit" between an obtained set of frequencies in a random sample and what is expected under a given statistical hypothesis.
Term
df
Definition
the number of values in the final calculation of a statistic that are free to vary. For simple one-way classifications the value of this is is defined as one less than the number of subsets.
Term
type II error
Definition
You have committed a this error if you have failed to reject the hypothesis...u thought it was true hyp...it was not
Term
type I error
Definition
You have committed a this error if you have rejected the hypothesis tested when it was true. More serious
more serious
Term
effect size
Definition
is a numerical way of expressing the strength or magnitude of a reported relationship, be it causal or not.

To know if an observed difference is not only statistically significant but also important or meaningful, you will need to calculate this.
It is calculated on a common scale -- which allows you to compare the effectiveness of different programs on the same outcome.
Term
power
Definition
is the probability that the test will reject the hypothesis tested when a specific alternative hypothesis is true.
To calculate it of a given test it is necessary to specify α (alpha, i.e., the probability that the test will lead to the rejection of the hypothesis tested when that hypothesis is true) and to specify a specific alternative hypothesis.
Term
basic calc for t test
Definition
employs the statistic - to test a given statistical hypothesis about the mean of a population (or about the means of two populations).
The test is often used to calculate the significance of observed differences between the means of two samples
_
t= x-u
_____o____
s/n
when s is sample standard deviation n=sample size df=1
Term
mean
Definition
indicates the point on the scale of measures where the population is centered.

the average of the scores in the population. Numerically, it equals the sum of the scores divided by the number of scores.
Term
median
Definition
the point on the scale of measures where the population is centered. The measure of a population is the point that divides the distribution of scores in half.
Term
mode
Definition
measures of central tendency that statisticians use to indicate the point (or points) on the scale of measures where the population is centered. It is the score in the population that occurs most frequently.
22234444444567 is 4
Term
nominal scale
Definition
names, eg. list of students in alphabetical order
Term
ordinal data
Definition
set of data, no zero eg. Likert scale
Term
inferential statistics.
Definition
you are trying to reach conclusions that extend beyond the immediate data alone.
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