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39 terms

Psychological Statistics

STUDY
PLAY
True or False: For all problems, we must use either the Addition Rule or the Multiplication Rule, but not both.
False
True or False: If an event is certain not to occur, its probability of occurrence equals 0.00
True
The probability of correctly calling 4 tosses of an unbiased coin in a row equals ____.
0.0625
The probability of rolling an even number or a one on a throw of a single die equals ____.
0.6667
If p(A and B) = 0, then A and B must be ____.
mutually exclusive
Probabilities vary between ____.
0 and 1
If m = 35.2 and s = 10, then p(X) for X £ 39 equals ____. Assume random sampling.
0.6480
The probability of drawing an ace followed by a king (without replacement) equals ____.
0.0060
Exhibit 8-3 Assume you are rolling two fair dice once. Refer to Exhibit 8-3. The probability of obtaining a sum of 2 or 12 equals ____.
0.0556
If events A and B are independent, then p(A and B) = ____.
p(A)p(B)
The nondirectional alternative hypothesis asserts that ____
the results of the experiment were due to chance alone
If alpha equals 0.05 and the probability level of your experiment is 0.04, you would ____.
reject the null hypothesis
In an experiment involving a nondirectional alternative hypothesis, the obtained result was 7 pluses and 1 minus. To evaluate the null hypothesis, which of the following probabilities would you use?
p(0) + p(1) + p(7) + p(8)
The alpha level ____.
is determined by the consequences of making a Type I and Type II error
If alpha equals 0.05, how many times out of 100 would you expect to reject the null hypothesis when the null hypothesis is in fact true?
5
If the alpha level is changed from 0.05 to 0.01, what effect does this have on beta?
beta increases
An alpha level of 0.05 indicates that ___
the probability of a Type II error is 0.05
true or false: If H0 is true and we reject it, we have made a Type I error.
true
True or false: f results are statistically significant, the independent variable must have had a large effect.
False
The primary reason we use a scatter plot in linear regression is ____.
to determine if the relationship is linear or curvilinear
If the value of sY|X = 4.00 for relationship A and sY|X = 5.25 for relationship B, in which relationship would you have the most confidence in a particular prediction?
A
If bY is negative, higher values of X are associated with ____.
lower values of Y
If bY = 0, the regression line is _
horizontal
The points (0,5) and (5,10) fall on the regression line for a perfect positive linear relationship. What is the regression equation for this relationship?
Y' = X + 5
If the regression line for predicting X given Y were X' = 103Y + 26.2, what would the value of X' be if Y = 0.2?
46.8
The regression of Y on X ____.
4. predicts Y given X
If the correlation between two sets of scores is 0 and one had to predict the value of Y for any given value of X, the best prediction of Y would be ____.
mean
True or False: If the correlation between two variables is 1.00, the standard error of estimate equals 0.
True
True or False? he least squares regression line insures the maximum number of direct hits.
False
The closer the points on a scatter diagram fall to the regression line, the ____ between the scores.
higher the correlation
Y can be most accurately predicted from X if the correlation between X and Y is ____.
-0.98
The proportion of variance accounted for by a correlation between two variables is determined by ____.
r squared
A correlation between college entrance exam grades and scholastic achievement was found to be -1.08. On the basis of this you would tell the university that ____.
they should hire a new statistician
When a correlation exists, lowering the range of either of the variables will ____.
lower the correlation
If N is small, an extreme score ____.
might have a large effect on robt
What is the slope for the points X1 = 30 and Y1 = 50, and X2 = 25 and Y2 = 40?
2.00
If 49% of the total variability of Y is accounted for by X, what is the value of r?
0.70
True or False: For a linear relationship to exist, all the points must fall on a straight line.
False
True or False: If the relationship is imperfect, the value of the correlation coefficient must be negative.
False