Chapter 5 Modeling Distributions Flashcards
What are empirical distributions?
distribution derived from empirical observations
What are analytic distributions?
a distribution where the CDF is a mathematical function.
What is the mathmatical definition of the exponential distribution?
When are exponential distributions seen in the real world?
Come up when we look at a series of events and measure the times between events, called interarrival times.
How do you test a data set to see if it has a exponential distribution?
You plot the complementary CDF ( which is 1 - CDF(x) ) on a log scale and if line produced has slope negative lambda then it is approximately an exponential distribution
What two parameters define the Normal Distribution?
mean and standard deviation
What transformation is used to test a data set for normal distribution fit?
There is no transformation to test a normal distribution.
What is a normal probability plot?
A graphical technique to identify departers from normality.
How do you test to see if a normal distribution is accurate for a data set?
Use a normal probability plot.
How is the lognormal distribution related to the normal distribution?
CDFlognormal(x) = CDFnormal( log(x) )
(if the log of a set of values have a normal distribution, the values have a log normal distribution)
What is the CDF of the Pareto Distribution?
CDF(x) = 1 - (x / xm ) -a
xm is min possible value
What visual test is used to indicate if an empirical distribution fit with the Pareto distribution?
On a log-log scale, the CCDF looks like a sraight line.
What distribution is the generalized Weibull distribution?
Exponenial Distribution
