how to

Question 1

take a random sample

Answer 1

1- Create a list of every unit in the population of interest, and give each unit a number between one and the total population size
2- Decide on the number of units to be sampled (call this number n)
3- Using a random-number generator, generate n random integers between one and the total number of units in the population
4- sample the units whose numbers match those produced by the random-number generator

Question 2

calculate goodness of fit (x^2)

Answer 2

x^2= sum of all classes [(observed-expected)^2/expected]

Question 3

How to calculate degrees of freedom for goodness of fit test

Answer 3

df= (number of categories) - (number of parameters estimated from the data) -1

Question 4

How do you find the P-value for goodness of fit?

Answer 4

• find the 5% critical value
• look at df for alpha of 0.05 on x^2 distribution table
• table will tell you critical value for x^2 for that many degrees of freedom

Question 5

Poisson distribution

Answer 5

Pr[x]= e^-u u^X/ X!
X= the number of events
u= the mean number of events per unit

Question 6

degrees of freedom in a contingency analysis

Answer 6

df= (#column-1)(#rows-1)