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COM 210 Quantative test #2
asdf
43
Agriculture
3rd Grade
03/06/2013

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Term
Research Hypothesis
Definition
Tentative statement about how 2 variables are associated in larger populations.
Term
Null hypothesis
Definition
no comparison or relationship between variables. Any difference in sample is random error
Term
T-Test definition
Definition
inferential statistic used to determine whether the mean for two groups of scores differs statistically and can be applied to entire population
Term
T-test variables
Definition
IV: Categorical (2 variables)
DV: Quantitative
Term
T-Test steps of hypothesis
Definition
1. formulate H1
2. Formulate H0
3. Select stat sig difference (p<0.05)
4. select correct test
5. Test stats for significance
6. make decision based on stats if stat sig and on HO & H1
Term
Statistically Significant
Definition
Probability, the smaller the p, the more confident we are of legit difference
Term
Significance level is same as
Definition
Two tailed or P value must be below 0.05. Reject H1 if greater than 0.05. not statistically significant. How certain we are no relationship exists.
Term
T-test variables
Definition
Degrees of freedom (df): N is considered
T: Farther from zero = stronger
P: lower than 0.05
Term
Effect Size for T-Test:
Definition
Describes size of a difference of an association in STANDARDIZED unit. (magnitude of difference) COHNAN'S D.
Term
Effect size measures for T-Test:
Definition
D = 0.20 (.15-.39) SMALL EFFECT
D = 0.50 (.4-0.74) MEDIUM EFFECT
D = 0.80 (.75-1.09) LARGE EFFECT
Term
Cohnen's D
Definition
Tells the magnitude of difference between two variables. If measures 0.05 very small or negligible effect.
Term
P (stat. sig) is tied to..
Definition
sample size
Term
Correlation Definition:
Definition
analysis used to measure strength of association between two quantitative variables. X scores tell us something about Y scores to help predictions
Term
Chi Squared (x2) variables
Definition
ID: Categorical
DV: Categorical
Term
R (Pearson's Correlation) variables
Definition
ID: Quantitative
DV: Quantitative
Term
Scatter Plot: and axis
Definition
Graphical depiction of a correlation
Y axis: DV (Vertical)
X axis: ID (horizontal)
Term
4 relationships of scatter plots
Definition
1. No relation
2. Positive linear relation
3. Negative (Inverse) Relation
4. Curvilinear (non-linear)
Term
No relation relationship
Definition
Knowing peoples level of variable X tells us NOTHING about variable y. Straight line. No shared Variance
Term
Positive linear relationship
Definition
as X increases, so does y.
As X decreases, so does Y.
The steeper the slope line, stronger the relationship
Term
Negative (Inverse) relationship
Definition
Scores move opposite of eachother, as X increases Y decrease, as Y increases X decreases.
Term
Curvilinear (non-linear)
Definition
relationship between X and Y is curved or it changes over time. Such as texting and driving (fear appeal works for certain amount of time until people ignore it)
Term
Examples of curvilinear
Definition
Sad dog commercial, worrying too much about grades makes 2nd guess and change.
Term
Pearson correlation (r)
Definition
provides numerical estimate of direct and strength of the linear relationship between two variables
Term
Pearson correlation (r) must be what two things??
Definition
Presumes relationship is linear
Possible range (-1.00-+1.00): closer to 1 is a stronger relationship
Term
Direction
Definition
sign of the correlation (+/-) depicts the direction of the relationship between X and Y
Term
Strength/what related to.
Definition
size of correlation depicts the strength of relationship between X & Y AND related to effect size.
Term
r = 0 or +/-
Definition
tells there is no relationship between X and Y
-complete overlap means will fall everytime!
Term
"Rule of thumb" for interpreting r
Definition
(Strength of relationship)
r = 0.1 SMALL
r = 0.24 MEDIUM
r = 0.37 LARGE
Term
Which is stronger?
r = 0.25 or r = -0.47
Definition
-0.47
Term
Coefficient of determination is called what in SPSS?
Definition
r2 linear
Term
Effect size for correlation (Coefficient of determination)
Definition
must square the r (r2) % of variance in variable X that is shared by Y value. r2=0.06 means 6% of X is shared by Y.
Term
r2 or effect size
Definition
exact percent of variance two scores share or the percent they move together
Term
CORRELATION DOESN'T EQUAL CAUSE. why?
Definition
just because there is a correlation between X and Y, by itself, doesn't show that X is the cause of Y
Term
3 correlation doesnt equal cause reasons
Definition
Co variation- are X and Y related? Is there a relationship?
Time order- Does X come before Y in time
Alternative explanations- Is anything besides X causing Y?
Term
Values needed in Correlation determination
Definition
r: Strength of relationshpi
r2: percent related X to Y
N: sample size
Sig fig: probability
Term
Chi square (X2)
Definition
inferential statistics used to address hypotheses nominal variables
Term
Chi Square Variables
Definition
IV: Nominal (2 categories)
DV: Nominal (2 categories)
Term
Statistical significance for chi square
Definition
compares what we observe/actually see vs what we expect by chance/average to see
Term
Degrees of freedom for chi test
Definition
Found on SPSS output (Rows-1)(Columns-1)
Term
Effect size measurement for chi test
Definition
Cramer's V
Term
Effect size for all three tests
Definition
Correlation: r2
Chi: Cramers
T-test: Cohens
Term
Cramer's V
Definition
takes on value from 0 to 1
0= one variable has no impact on other
1= one variable totally determines the other
Term
Rule values for Cramer's V
Definition
0.10= SMALL EFFECT
0.24= MODERATE/MEDIUM EFFECT
0.37= LARGE EFFECT
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