S2 Flashcards
What is a population?
A collection of items
What two things can a population be?
Finite and Infinite
What is a finite population?
Where each individual can be given a number
Give an example of a finite population?
A class
What is an infinite population?
Where each individual can’t be given a number
Give an example of an infinite population?
Stars
What is a census?
An investigation where every member of the population is evaluated
What is a sampling unit?
A single member of the population
What is a sampling frame?
A list of sampling units
What is a sample?
A selection of sampling units from a sampling frame
What is a statistic?
A quantity calculated only from data in a sample - no unknown
Give two things that a statistic won’t contain?
Mean or standard deviation
Give three advantages of a census?
- ) Unbias
- ) Accurate answer
- ) Every member is taken account of
Give four disadvantages of a census?
- ) Takes a long time
- ) Costly
- ) Difficult to ensure everyone is surveyed
- ) Can result in destruction of the whole population
Give four advantages of a sample?
- ) Representative of a large population
- ) Essential if testing involves destruction
- ) Data is more readily available
- ) Usually cheaper
Give three disadvantages of a sample?
- ) Can be bias
- ) Not every ones opinion is used
- ) Two samples unlikely to give the same result
Name two ways no skew can be found?
Mean = Median = Mode
Q3 - Q2 = Q2 - Q1
Name two ways negative skew can be found?
Mean Q3 - Q2
Name two ways positive skew can be found?
Mode > Median > Mean
Q3 - Q2 > Q2 - Q1
What is a sampling distribution?
The distribution of all possible values of Y
Name four conditions of the binomial distribution?
- ) Two outcomes ( success and failure)
- ) Fixed number of trails
- ) N trials are independent
- ) Probability is constant
Name four conditions of the poisson distribution?
- ) Events must occur singularly
- ) Lambda is constant
- ) Events occur independently
- ) Events occur randomly
Name two conditions for estimated the binomial by the poisson?
1.) p is small 50
Name two conditions for estimating the binomial by the normal?
- ) p is near 0.5
2. ) n is large >20
Name a condition for estimating the poisson by the normal?
Lambda is large >10
When estimating the binomial by the poisson how do you calculate lambda?
Lambda = np
When estimating the binomial by the normal how to calculate the mean and standard deviation?
Mean = np
Standard deviation = sqr.(npq)
When estimating the poisson by the normal how to you calculate the mean and standard deviation?
Mean = lambda
Standard deviation = sqr.(lambda)
What is a hypothesis?
A statement concerning a population parameter
What is the critical region?
The set values of X which you reject H0 and accept H1
What is meant by the significance level?
The probability of incorrectly rejecting H0
