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Stat Test 2
Stat Test 2
78
Mathematics
Undergraduate 4
03/06/2015

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Cards

Term
What is the correlation Coefficient?
Definition
r, pearson r
Term
what is "r" or the pearson "r" called?
Definition
the correlation coefficient
Term
What does "r" measure?
Definition
the degree of linear relationship between two continuous variables
Term
Why is the pearson "r" used?
Definition
because most tings have continuous variables
Term
What are the 4 things that a scatter plot shows you?
Definition
Directionality
Linear relationship
presence of outliers
strength of association
Term
What is an example of a High strength of association?
Definition
[image]
Term
What is an example of a weak association?
Definition
[image]
Term
What types of directionality are there?
Definition
Negative and Positive
Term
What is an example of positive directionality?
Definition
[image]
Term
What is an example of a negative association?
Definition
[image]
Term
What two things do you do when there is an outlier?
Definition

-make sure you didn't make a transcription error

-investigate the cause of the score

Term
How do you get the total sum of the cross product?
Definition
(x-xbar)(y-ybar)
Term
What should the top number in the computational method always match?
Definition
the sum of the cross product
Term
What does "r^2" and "1-r^2" represent on a ven diagram?
Definition
[image]
Term
What is the sum of the cross product called?
Definition
the Covariation
Term
What is the range of "r"?
Definition
-1 to +1
Term
What are the numbers and ranges for levels of correlation?
Definition

+/- .80 - 1.0 = very strong

+/- .60 - .79 = strong

+/- .40 - .59 = moderate

+/- .20 - .39 = weak

+/- .01 - .19 = very weak

0 = none

Term
How would you say the strength of a correlation in a sentence? (exp. r=.7, x=hours studied, y=test grade)
Definition
There is a strong positive relationship between ours studied and test grades.
Term
What is "r^2" also known as?
Definition
the coefficient of determination
Term
What is the symbol for the coefficiet of determination?
Definition
r^2
Term
What is "1-r^2" also known as?
Definition
the coefficient of nondetermination
Term
What is the symbol the coefficient of nondeterminiation?
Definition
1-r^2
Term
In a correlation ven diagram, what represents the X values and what represents the Y values?
Definition
[image]
Term
[image]How would you interpret the results of the diagram in terms of X and Y? (X=hours studied, Y=test score)
Definition
51% (X) of test scores can't be explained by hours studied, but 49% (Y) can be explained by hours studied.
Term
What mathematical equations represents X and Y in correlation questions?
Definition

X = 1-r^2

Y = r^2

Term
What variable is always the dependent variable?
Definition
Y
Term
What variable s always the independent variable?
Definition
X
Term
Which variable always comes chronologically first?
Definition
The Independent variable or X
Term
What are other terms for "Predication"?
Definition

Simple Linear Prediction

Simple Linear Regression

Term
What does Simple Linear Regression mean (SLR)?
Definition
One X and one Y
Term
What is the equation for multiple linear regression (MLR)?
Definition

Y' = Bo + B X

               '

Term
When using a prediction equation when is the only time you can truly use it?
Definition
when an observed X value i within the range of X scores used to make the equation
Term
How do you determine the average increase/decrease in correlation per unit changed X?
Definition

look at the value attached to X in the line equation or "Multiple Linear Regression" equation

 

=ax+b

Term
What are other names for Sy.x?
Definition

-standard error of prediction

-standard error of regression

Term
Anytime you see a "S" start thinking of what?
Definition
standard error
Term
What is the equation for Sy.x?
Definition
SDy sqrt(1-r^2)
Term
What is the general rule of Sy.x?
Definition
the number should be a low value because it means predictions will be lower and a high correlation
Term
What is a "line of best fit"?
Definition
the line drawn through a correlation graph that segments the points in the most common way
Term
What really places the line of best it?
Definition
b not and b sub prime
Term
What is the equation for the lengths of the lines that stem off of the line the best fit
Definition
sum of(y-y')^2
Term
What is the equation for the error of sums of squares
Definition
sum(y-y')^2
Term
What is this called = sum(y-y')^2 how else is it found?
Definition

-error of sums of squares

-adding up the lines that stem off of the line of best fit

Term
What are the least squared estimators
Definition
b not and b sub prime
Term
Why is the Least squared estimators called that?
Definition
because they put th line in a data set so that the Error Sums of Squares is as small as possible
Term

How do you verbalize the interpretation of Sy.x?

y' = 8.3

S = Sy.x

Definition

68 times out of 100 someones true test score is not more than 2.26 pts. from 8.3

(68 as in 68% under the curve or one standard deviation in both ways or 34%)

Term
What are other words for "Direct" and "Inverse"?
Definition
Positive and Negative
Term
What is B sub 1?
Definition
the slope of the line of best fit
Term
How would you interpret the venn diagram?
Definition
__% of variability in ___ was due to ___ while ____ can't be explained by ___.
Term
_____ data will give consistent results?
Definition
reliable
Term
True Knowledge = ?
Definition
observed score +/- Error
Term
Content Validity...
Definition
should be related to % with emphasis placed on a topic
Term
What are the types of Criterion Validity
Definition
Concurrent Validity
Predictive Validity
Construct Validity
Term
What is concurrent validity? What is an example?
Definition
happens at the same time
exp. Body fat % with men and women
Term
What is predictive validity? What is an example?
Definition
validity in the future
exp. SAT score should predict how well you will do in college
Term
What is construct validity? What is an example?
Definition
Can't see, feel or touch the measured variables.
exp. motivation, feelings
Term
What are the parallel forms of reliability testing?
Definition
White and Yellow tests
Term
What is an example of Interrater reliability?
Definition
the degree a panel of judges rates the same performance
Term
What is an example of intrarater reliability?
Definition
how consistant is any one judge when he/she scores something
Term
What I internal consistency?
Definition
one test at one time
Term
How do you interpret Y'?
Definition
for every X studied Y goes up/down on average ____ points
Term
What is the equation for b not?
Definition
b not = y bar - (b sub 1)(x bar)
Term
How do you interpret b not?
Definition
it is the y intercept on the line of best fit
Term
What 5 things do you keep in mind when designing graphs?
Definition
1. plan, plan
2. present one idea per chart
3. make sure that the scales are proportionate
4. simple is best
5. no junk
Term
What is frequency distribution?
Definition
a summary of raw data that indicates how often each data point occurs.
Term
What is an appropriate input of the "input range" field in excel?
Definition
$A$1:$A$26
Term
What is an "Ogive" in excel?
Definition
a visual representation of a cumulative frequency distribution
Term
Why is an "ogive" useful?
Definition
it shows the change in the number of scores within each class interval
Term
What is the difference between a bar chart and a column chart?
Definition
a bar chart has the bars going horizontally and a column chart has the bars going vertically
Term
When should you use a Column chart?
Definition
to compare items to one another or examine changes over time
Term
When should you use a Bar chart?
Definition
to compare items to one another or examine changes over time
Term
When should you use a line chart?
Definition
to display data that are continuous over time like trends
Term
When should you use a Area chart?
Definition
to emphasize the amount of change over time
Term
When should you use a scatter chart?
Definition
to show the relationship between two data points across several cases
Term
What is the excel formula for SD of a population?
Definition
=STDEV.P
Term
What is the excel formula for SD of a sample?
Definition
=STDEV.S
Term
What is the excel formula for variance of a population?
Definition
=VAR.P
Term
What is the excel formula for variance of a sample?
Definition
=VAR.S
Term
What menu is Central Tendancy under in Excel?
Definition
the Descriptive Statistics menu
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