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Date Submitted: 04/02/2013 04:25 AM
Lab Test #1 Cheat Sheet
Binomial:
* Discrete distribution
* Sequence of n independent events
Only one of two possible outcomes
Cumulative =BINOMDIST(number of objects, number of trials,probability,1)
Eg.
Poisson distribution
* Discrete distribution
* Succession of events happening over some interval
* Events occur individually
* Their timing or spacing is unpredictable
* Events are independent
Cumulative =POISSON(number of trials, avg rate/hour,1)
E.g.
Exponential Distribution
* Continuous distribution
* Randomly occurring events occurring over some continuous interval
* Describes length of an interval between events in situations where there is a succession of independent, random events
Cumulative =EXPONDIST(interval (hours), avg rate/hour,1)
Eg.
Excel Functions:
1. NORMDIST gives the probability that a number falls at or below a given value of a normal distribution
2. NORMINV is the inverse of the NORMDIST function. It calculates the x variable given a probability
3. NORMSDIST translates the number of standard deviations (z) into cumulative probabilities
4. NORMSINV is the inverse of NORMSDIST function. Given the probability that a variable is within a certain distance of the mean, it finds the z value
Cumulative =NORMDIST(<length, mean, stdev, 1)
Degrees of Freedom: a mathematical restriction that we need to put in place when we calculate an estimate one statistic from an estimate of another
* Each item being estimated costs one degree of freedom. The remaining degrees of freedom are used to estimate variability
DoF = n-1-(#of estimated parameters)
Chi-square test: 1. Find the expected frequencies, 2. Find the errors for each interval, 3 add up the error, the sum is X2 calc-6.3463143992, 4. Find the degrees of freedom, 5. Find X2 using =0.05 significance level
If X2 calc < X2 crit., then not too much errors, observed follows distribution
Chi-square...