Stats Test 2 Prep
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Situation in which the outcome is unknown before
it happens...give example
- Random Experiment
- rolling die
This is the most basic outcome of a random experiment
(simple event)..give example
- Sample Point
- head or tail for a coin toss
This is a collection of sample points
This is a collection of all sample points in the experiment
The probability of an event (or simple event) is simply what you think it is , so long as the values of probability are observed...give example
- Personal probability
- flipping a coin and peaking
The probability of a (simple) event happening is
the “long-run” relative frequency of that event
Relative frequency interpretation
In the event that both A and B occur at the same time it is called an...
The probability of either A or B happening is called a ?
Give the 2 terms assigned for when two events CANNOT happen at the same time
- Mutually exclusive
What is the formula for (A u B)
P(A)+P(B)-P(A n B)
What is the formula for (A u B) if A and B are mutually exclusive..explain
- P(A)+P(B)-P(A n B)=P(A)+P(B)
- this is because A n B can't happen together
What is the formula for conditional probability? (A|B)
P(A n B)/P(B)
In the formula for A|B can you calculate A n B directly?
No, it must be either given or extrapolated from a different formula
If knowledge of one event happening does not change the probability of the other one happening, the two events are said to be...
What does this mean: A u B u C...
probability of at least one of these events have happening
What does this notation mean: A n B n C..
These events have all happened
What does this mean: A u B n C
Nothing..has no meaning...must know which one to do first
What does this notation mean: (A u B) n C
First the probability of the union of event A and B then the probability of the intersection of one of those with C
Based on the distributive rule, what does this equal: A u (B n C)
(A u B) n (A u C)
Based on the distributive rule, what does this equal: A n (B u C)
(A n B) u (A n C)
This is a sample that represents our population well
If a sample is not representative of the entire population, it is called:
What are the 3 types of sample bias?
- Response bias
- Non-response bias
- Sampling bias
What is a response bias..give example
- Measurement obtained that is incorrect
- lies in a survey
- bad scale
What is a non-response bias?..give example
- Simply getting no response at all
- anything involving volunteer answers
- scale you can't use
What is Selection bias?...give example
- Taking a sample that is not from your general population
- Wanting a survey of the UConn population but only surveying grad students
How do you control sample bias
by taking simple random samples
A list of everything in your population is called a...
What is a convenience sample, and would it be a good representation?
- Simply sampling those around you at the time
- bad representation
What is cluster sampling?...and is it a good representation
- Breaking the population into groups and taking simple random samples of each group
- good representation
What is stratified sampling and how good of a representation is it?
- Breaking the population into different groups which have members with similar properties then doing SRS
- very good representation
This type of random variable can on a particular value
Discrete random variable
This type of random variable can take on any value in one or more intervals
Continuous random variable
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