Unit 3
What is the easiest sampling method to do?
Convenience sampling
What is a continuous variable?
A variable with infinite values with no gaps
When is point estimate biased?
When the expected value is not equal to the true population parameter
What is the Ho for a X2 test for goodness of fit?
The claimed distribution of the categorical data
What is the symbol for the slope of a line of linear regression?
β
Name the three forms of sampling bias.
Under coverage
Nonresponse
Response Bias
How does dividing a random variable by a constant affect the standard deviation?
The new standard deviation is old standard deviation divided by the constant
What is the central limit theorem?
When a sample mean distribution has a sample size equal or larger than 30, it is approximately normal.
What is the test statistic for X2 for goodness of fit?
∑(O-E)2/E
O = Observed Count
E = Expected Count
What test is used for the slope of regression?
A t-test
What is a confounding variable?
A variable that unintentionally influence the response variable skewing the result data
What is the check for binomial random variables and geometric random variables?
BINS and BITS
What is the standard deviation of a sample mean?
SE = σ / √n
What is the formula for expected counts?
(row total * column total)/ grand total
Subtract two from the sample size
What is the difference between an observational study or experiment?
In an experiment, treatments are imposed
What is the formula for a binomial random variable?
The number of successes*the chance of success*the chance of failure
What is the standard deviation of a sampling distribution for proportion?
SE = sqrt[p(1-p)/n]
If the Ho is rejected, what do you do in a X2 test after interpreting the p-value and concluding?
Follow up analysis
What is the confidence interval formula for a t-confidence interval?
b± t*(SEb)
What is the difference between cluster sample and a stratified random sample?
Stratified random sample groups are homogenous
Cluster sample groups are heterogenous
The simple random sample of stratified random sample groups are taken
What the formula for geometric distribution?
the probability of failure number of failures * the probability of success
What is the mean for a sampling distribution for proportions and means?
x̄p = p
x̄μ = μ
What are the criteria for each X2 test.
X2 for the goodness of fit (1 sample, 1 variable)
X2 for homogeneity (2 sample, 1 variable)
X2 for independence (1 sample, 2 variable)
What is the acronym for the checks for a t-test for slope? And what does each letter mean?
L-Linear
I-Independent
N-Normal
E-Equal SD
R-Random