Stats Flashcards
(28 cards)
What is the variance?
How far the spread of data is from the mean
How do you work out the variance?
Var(x)=E(x^2)-(E(x))^2
What is the form of a binomial distribution?
B(n,p)
What makes it a binomial distribution?
All the trials are independent of each other and there are a fixed number of trials with two outcomes
What is the probability of a binomial distribution?
P(X=x)=nCx x p^x x q^n-x
What is the binomial expected value?
E(x)=pn
What is the expected value of a geometric distribution?
E(X)=1/p
What is the general form of a geometric distribution?
Geo(p)
What is P(X=x)
Pq^x-1
What is P(X>x)
(q)^x-1
What is P(X
1-(q)^x
What makes it a geometric distribution?
There isn’t a fixed number of trials and the trials occur until a successful is achieved
What makes it a permutation?
Order matters
What makes it a combination?
Order doesn’t matter
How do you work out expectation?
E(X)= sum of r x P(X=r)
How do you work out the mean from a frequency table?
X=sum of fx/ sum of f
How do you work out varience?
Sum of fx^2/sum of f - (sum of fx/sum of f)^2
How can you work out P(BB)
Multiply the probabilities together
How can you work out P(BB)
Multiply the probabilities together
What does mutually exclusive mean?
This means that both events cannot happen
What does “or” mean?
This means both can happen symbolised by U
What is P(A or B)?
P(A) + P(B) - P(AnB)
What does P(A/B) mean?
The line means given which means the probability of A given B has already hapoened
How can you work P(A/B)?
P(A and B) / P(B)
