Stats Flashcards
A n B
Intersection
A U B
Union
P(A|B) =
P(A|B’) = P(A)
P( A U B ) =
P(A) + P(B) - P(AnB)
P(B|A)
P( B n A) / P(A)
Standard normal distribution mean and standard deviation
Mean = 0
Standard deviation = 1
sample mean of a normally distribute random variable X ~ N(u , ó^2 / n)
Z = ( X - u) / ( ó / root n )
with Z ~ N( 0, 1)
Population
Set of items that are of interest
Census
Observes or measured every member of a population
Sampling units
Individual units of population
Sampling frame
Sampling units individually named or numbered to form a list
Simple random sample
Size of n is one where every sample of size n has an equal chance of being selected
Systematic sampling
Required elements are chosen at regular intervals from an ordered list
Stratified sampling
Population is divided into mutually exclusive strata and a random sample is taken from each
Quota sampling
Interviewer or researcher selects a sample that reflects the characteristics of the whole population
Opportunity sampling
taking the sample from people who are available at the time the study is carried out and who fit the criteria you are looking for
Continuous variable
Any valuable in given range
Discrete variable
Set values in a specific range
Outliers
Q3 + k(Q3 - Q1)
Q1 - k(Q3-Q1)
What is cleaning the data
Removing the anomalies
What is the vertical scale on histogram
Frequency density = frequency / class width
Bivariate data
Pairs of values for two variables
Regression line
Y = a + bx
Mutually exclusive
P( A or B) = P(A) + P(B)
Independent events
P(A and B) = P(A) x P(B)
What happens if test statistic falls within critical region
Reject null hypothesis
What is critical value
first to Fall inside of the critical region
What is the actual significance level of a hypothesis test
probability of incorrectly rejecting null hypothesis
