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What is the definition of each confidence interval procedure? What are their conditions?
One Sample Z-Interval for a population proportion
Estimating the proportion of of successes in a single population
Conditions of a One Sample Z-Interval for a population proportion
Independence:
Data collected using a random Sample
Sample Size n is ≥10% of N
Approximately Normal:
Large counts n(p̂ )≥ 10 and n(1-p̂ )≥10
What is the form of Confidence Intervals
CI= point estimate ± margin of error
What is the point estimate?
Value of random variable
Ex: p̂ or x̄
How do you find moE?
critical value(standard error of statistic)
2 sample Z interval for a difference in proportions
Estimating the difference in proportions
When is it appropriate to use a 2 sample Z interval for a difference in proportions?
When either:
2 random samples have been selected
subjects are randomly assigned to 2 random groups
Conditions of a Two Sample Z-Interval for a population proportion
Independence:
Data collected using TWO random Samples
Sample Size n is ≥10% of N for BOTH samples
Approximately Normal:
Large counts n(p̂ )≥ 10 and n(1-p̂ )≥10 for BOTH samples
How do you find the confidence interval for a difference in proportions?
(p1-p2)± z*(standard error of statistic)
2 sample T interval for a difference in means
Estimating the difference in means
One Sample T-Interval for a population mean
Estimating the mean in a single population
Conditions of a One Sample Z-Interval for a population proportion
Independence:
Data collected using a random sample
Sample Size n is ≥10% of N
Normal Distribution:
n is greater than or equal to 30
If n < 30 data MUST be free from strong skewness or outliers
How do you find T* using calculator?
Inverse t distribution
area: 1 - C% as a decimal…divide that value by 2
df: n-1
How do you find Z* using calculator?
Inverse norm distribution
area (Central): C% as a decimal
mean: 0
SD: 1
paired t-test
sample comes from
