MIS 301 Shaul Quiz 2
Central Limit Theorem - correct answer ✔The theory that, as sample size
increases, the distribution of sample means of size n, randomly selected,
approaches a normal distribution.
for a sample size to be normally distributed it must be - correct answer
✔over 30
standard error of the mean - correct answer ✔the standard deviation of a
sampling distribution
standard error of the mean formula - correct answer ✔σ (subscript X bar) = σ
/square root of n
mu = x-bar +/- Z (subscript: α/2)* (σ/square root of n) - correct answer ✔x-
bar: sample mean
Z: confidence level coefficient
α: probability of an area beyond the confidence interval
σ/square root of n: standard error of the mean
confidence interval formula - correct answer ✔mu = x-bar +/- Z (subscript:
α/2)* (σ/square root of n)
if you increase the confidence level - correct answer ✔the probability of an
area beyond the confidence level drops
normal distribution formula - correct answer ✔Z = (x-mu)/σ
, Z = (x-mu)/σ - correct answer ✔X :random variable
mu: population mean
σ: standard deviation
sample mean formula - correct answer ✔t = (x-bar-mu)/(s/square root of n)
t = (x-bar-mu)/(s/square root of n) - correct answer ✔x-bar: random variable
mu: population mean
(s/square root of n): standard error of the mean
properties of the t-distribution - correct answer ✔- symmetrical, bell shaped
- mean= 0, SD> 1
- shape changes depend on sample size
- as n decreases, variation goes up
- accounts for the greater uncertainty associated with small samples
when to use t-distribution - correct answer ✔when the sample is less than 30
and we don't have sigma
you can either have a _______ confidence level and a _______ confidence
interval or vice versa but you can't have both - correct answer ✔high; large
95% CL - correct answer ✔z = 1.96
90% CL - correct answer ✔z = 1.645
Central Limit Theorem - correct answer ✔The theory that, as sample size
increases, the distribution of sample means of size n, randomly selected,
approaches a normal distribution.
for a sample size to be normally distributed it must be - correct answer
✔over 30
standard error of the mean - correct answer ✔the standard deviation of a
sampling distribution
standard error of the mean formula - correct answer ✔σ (subscript X bar) = σ
/square root of n
mu = x-bar +/- Z (subscript: α/2)* (σ/square root of n) - correct answer ✔x-
bar: sample mean
Z: confidence level coefficient
α: probability of an area beyond the confidence interval
σ/square root of n: standard error of the mean
confidence interval formula - correct answer ✔mu = x-bar +/- Z (subscript:
α/2)* (σ/square root of n)
if you increase the confidence level - correct answer ✔the probability of an
area beyond the confidence level drops
normal distribution formula - correct answer ✔Z = (x-mu)/σ
, Z = (x-mu)/σ - correct answer ✔X :random variable
mu: population mean
σ: standard deviation
sample mean formula - correct answer ✔t = (x-bar-mu)/(s/square root of n)
t = (x-bar-mu)/(s/square root of n) - correct answer ✔x-bar: random variable
mu: population mean
(s/square root of n): standard error of the mean
properties of the t-distribution - correct answer ✔- symmetrical, bell shaped
- mean= 0, SD> 1
- shape changes depend on sample size
- as n decreases, variation goes up
- accounts for the greater uncertainty associated with small samples
when to use t-distribution - correct answer ✔when the sample is less than 30
and we don't have sigma
you can either have a _______ confidence level and a _______ confidence
interval or vice versa but you can't have both - correct answer ✔high; large
95% CL - correct answer ✔z = 1.96
90% CL - correct answer ✔z = 1.645
