Point estimate of  for small samples ( n < 30)  is still 

Use Student  t - scores rather than z - scores
 
   

And  is replaced by the Student t Distribution
            (Table A-3) to get 

    Table A-3 is a minimal summary of several tables like table A-2

     Flatter bell curve,  greater variability, picture pg. 308

Reading the Student t tables

#2
 
 

#4
 
 
 

Degrees of freedom = n - 1

Properties of Student  t  Distribution   -   pg. 307, 308

Conditions for Using the Student t  Distribution - pg. 308
 
Margin of Error 
    is how much  standard deviations from mean for sample means

    (will tend to be larger for student t )
   

          where  has  n-1 degrees of freedom

Confidence Interval
 

                     where 
 

 #6
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Choosing the Appropriate Distribution    z  versus  t     pg. 311 Flowchart

#10
 
 
 
 
 
 
 
 
 
 
 
 
 

#14
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

**#16  (use   because know  )