prob of difference between proportions and means Flashcards
Large Counts Condition- “the shape of the sample distribution p hat1- p hat2 is ~N because [ n1(p1), n1(1-p1), n2(p2), n2(1-p2) ] are all greater than or equal to 10
normality check for proportions
The shape of the sampling distribution xstat1-xstat2 is ~N because BOTH samples are greater than or equal to 30
OR
The shape of the sampling distribution xstat1-xstat 2 is ~N because both samples come from populations already approximately normally distributed
normality check for means
st.d p hat1-p hat2 = square root of p1(1-p1)/n1 + p2(1-p2)/n2
In REPEATED SAMPLES of 100 registered cars from Angelica’s state and 70 cars from Kyle’s state that are manufactured in the US, the difference in sample proportions OF cars made by US manufacturers is typically 0.0684 away from the POPULATION PROPORTION OF 0.21
Calculate and interpret st.d of sampling distribution of p hat1- p hat 2
st.d samplemean1-xstat2 = square root of pop st.d1 (squared!!) of /n1 + pop st.d 2(squared!!) of /n2
Interpret: In REPEATED SAMPLES of 20 cups filled with large setting and 25 cups filled with medium setting the difference OF sample mean (!!) AMOUNT OF LIQUID is typically 0.205 oz away from the population mean difference (!!) of 10 oz
Calculate and interpret st.d of sampling distribution of samplemean1-samplemean 2
samplemean1-samplemean2 - pop mean d / pop. st.d
z score
