Stats terminology and tests 2 Flashcards
What is the standard error?
The amount of lack of confidence in the estimate of our mean
Low standard error means what level of confidence in the mean?
High
High standard error means what level of confidence in the mean?
Low
Standard error formula?
Standard deviation/(sqrt(n))
Out of two populations with the same mean and sd but different population sizes, which one would have a larger standard error?
The one with a larger population
What is a z score?
The amount of standard deviations away from the mean that one data point is
Mean = 100, sd is 5, what is the z score of 120?
+4
Mean = 100, sd is 5, what is the z score of 85?
-3
Characteristics of a Bernouli trial?
Success/failure, probability of success is the same in every trial, trials are independent
What is a chi squared test used for?
To see if the observed results fit with expected results
What is a chi squared test suitable for?
frequency data
What do you do with a chi squared value?
Look it up in a chi squared table using the degrees of freedom
Degrees of freedom?
N-1
How do you get the p value from a chi squared test?
looking it up in a chi squared table
When is yates correction used?
When doing chi squared with two values
What is yates correction?
Subtract 0.5 from each value of O-E ignoring the sign (|O-E|-0.5)
Limits to chi squared test?
No expected category should be less than 1 observation
No more than 1/5 of the expected values should be less than 5
What can be used as a test of association?
chi squared test
What must done before using a chi squared test as a test of association?
Contingency table
How to find the expected value of a cell in a contingency table?
(rowtotal*columntotal)/overalltotal
Degrees of freedom when using a contingency table?
(rows-1)*(columns-1)
What are the two tests used for categorical data (frequency data)?
Chi squared or binomial
What test is used when there is more than two categories of categorical (frequency) data?
Chi squared
What tests are used when there is two categories of categorical (frequency) data?
binomial or chi squared
What does a regression analysis do?
Fits a straight line against a scatterplot
X axis on a regression analysis?
Independent or predictor variable (variable that causes the response) (thing you have control over)
Y axis on regression analysis?
Dependent or response variable
