Probability Flashcards
State the value of XC0 where X is any number
Always 1
Name the distribution where each variablein a discrete data set is equally likely to be chosen
Discrete uniform distribution
What must be true in binomial distribution
Two outcomes
Probability of each event stays constant for each trial
Trials are independent
Variable must be discrete
What do n and p mean in X~B(n, p)
n= number of trials p= probability of success
What is binomial PD used for
P(X=x)
What are the features of discrete random variables
Set values
Sum of probabilities is 1
What does |X–3| mean
Modulus X–3 (absolute value)
What is the critical region
Where H0 is rejected
When using cumulative probability why must f(2.6) be rounded to f(2) not f(3)
We don’t know the distribution up to 3 so must assume it’s the same as 2
What is binomial CD used for
P(X
When are two or one tail test used
Two tailed = determine bias
One tailed= determine what it’s biased towards
What is the null hypothesis
Original probability
What is the alternative hypothesis
Probability of Claim or suspicion
When the probability is outside of the critical region what occurs
We fail to reject the null hypothesis
What happens the the significance level in a two tailed test
Halfed (for split between top and bottom critical regions)
Name the steps in testing a hypothesis
Set probability
State null and alternative hypothesis
State binomial distribution using P of null hypothese
Find P of unusual
Compare to significance level
State whether you reject or fail to reject the null hypothesis
State what this suggests in context
What is the actual significance level
The probability as a percentage of:
the first value in the critical region at the higher end
or
the last value in the lower end
How do you calculate the CR
List values of X and find cumulative probability
Values below SL (lower end) and values above 1 – SL (upper end) are in the critical region
What is the difference between nPr and nCr
P= permutation so order matters
C= combination so order doesn’t matter
P(X)=0.3
P(C)=0.6
X and C are mutually exclusive so find P(XUC)
0.3+0.6=0.9
events O and Z are independent
find P(Z ⋂ O) if
P(O) =0.9 P(Z)=0.2
0.9x0.2=0.18
How do you prove A and B are independent?
P(A)=P(A|B)
How do you prove A and B are mutually exclusive?
P(AnB)=0
Why is P(BnV)= P(V) x P(V|B) wrong?
it should be P(V) x P(B|V)
What is the significance level?
The probability of rejecting the null hypothesis when it’s true
