Stats Midterm 2 Flashcards
(22 cards)
Empirical Rule
68, 95, 97.7 %
- only works for normally distributed, symmetric data
- Mue + 1 standard deviation, etc
a contineous random varible x is normally distributed if
that distribution hasa graph that is symmetric and bell shaped
how many decimals do you round in Z score tables
2
what is the transformation that turns raw data into z score values
standardization
- always calculate Z values form the lefthand side
x bar is
SAMPLE mean
what happens if the z value is not on the table
probability is 0.
uniform distribution
values spread evenly over a full range of possibilities. rectangle
standard normal distribution has
a mean of 0 and a standard deviation of 1
The Central Limit Theorem:
As the sample size n
increases, the sampling distribution of sample means X
approaches a normal distribution.
parameter
characteristic of a population
Proportion letter
P
what can be estimated
- mean
- proportion
- standard deviation
( X bar - E < E < X bar + E ) is what and what is E
an estimate
E is the estimator
alpha is what
significance level
degree of confidence is what
how sure you are that it will be between two values
critical value formula
Z Alpha/ 2
significance levels are where
theyre the two ends of the tails
when do you use t tables
when n is small (<30)
how to find the critical value
1- (alpha/2)
will the margin of error get bigger or smaller with a bigger n
smaller
what are three things that affect the margin of error
-degree of confidence
- standard deviation
- n (sample size)
estimating the proportion includes
p hat and q hat
