Stat Test 2
If two events have no outcomes in common, they are said to be?
Mutually exclusive
Suppose i roll two fair dice. How likely is it that I will roll snake eyes?
6x6= 36 1/36 chance
% of curve 2 standard deviation
95%
% of curve 3 standard deviation
99.7%
random phenomenon
A phenomenon is random if we know what outcomes could happen, but not which particular values will happen.
The least squares regression line for predicting y from x is y=500-20x, what is the predicted value of y when x=10?
Answer: 300
Which statistical measure is not strongly affected by a few outliers in the data? A.) The Mean B.) The Median C.) The Standard Deviation D.)The correlation coefficient
B.) The Median
Which Correlation indicates almost no straight-line relationship? A.) -0.84 B.) 0.75 C.) 1.5 D.) 0.04 E.) 0.99
C.) 0.04
Suppose we want to study the relationship between the cost of peaches and the number of peaches sold. Which is the explanatory variable? Which is the response? Positive or negative correlation?
EX: COST OF PEACHES R: #OF PEACHES NEGATIVE
What does R^2 tell us?
How successful the regression was in explaining the response variable
evidence of causation
Plausible Association is strong Consistent
Where does the best evidence for causation come from?
Randomized comparative experiments
The ______ of a statistic indicates what values the statistic takes in repeated samples from the same population and how often it takes those values.
Sampling distribution
What is the most common way to display the relationship between two quantitative variables?
Scatterplot
R=0.1 Strength of relationship?
WEAK
Is r affected by outliers?
Yes. Strongly
WHATS ANOTHER NAME FOR THE TEST STATISTIC?
Z-SCORE
statistic
a number that describes a sample
type 2 error
false negative
Type 1 error
false positive
haphazard
marked by lack of any plan, order, or direction
Parameter
numerical summary of a population
If a significance test gives P-value 0.005
we do have convincing evidence against the null hypothesis.
y = a+bx y = x= b= a=
y = how far up x = how far along b= slope (how steep the line is) a = the Y Intercept (where the line crosses the Y axis)
least squares regression line equation
y = mx + b
LEBRON makes 80% of his free throws. How could we assign random digits to simulated his free throws?
0,1 = Miss 2,3,4,5,6,7,8,9 = Make
% of curve 1 standard deviation
68%
confidence level
A PROBABILITY THAT SAYS HOW OFTEN IN MANY SAMPLES THE METHOD WOULD PRODUCE AN INTERVAL THAT CONTAINS THE ACTUAL PARAMETER VALUE
What is the correlation between size of engine and horse power? Which is the response? Which is the explanatory?
Positive Correlation R=Horsepower E=Engine Size
The response variable should always be on which axis?
The Y-axis
Suppose flights at a large metro airport are on-time 68% of the time and late 32% of the time. How could we assign random digits to represent this probability model? Make sure to know equation of proportions too.
Using random digits table: 00-68 = on time 68-99 = late Pr(on-time) = 0.68 Pr(late) = 0.32
extrapolation
projecting outside data set. Risky.
How is correlation usually abbreviated?
r
What cab we say about the relationship between correlation r and the slope b of the least-squares line for the same set of data?
r (correlation) b(direction) always have the same sign( + or - )
chance behavior
unpredictable in the short run but has a regular and predictable pattern in the long run
null hypothesis
usually a statement of "no effect" or "no difference"
What values does r always fall under?
-1 and 1
How do you find the proportion of the variation in y that is explained by the least squares regression line?
(r^2)
What is the correlation between size of engine and gas milage?
Negative correlation.
