Revised confidence intervals vocab Flashcards
Confidence Intervals
Estimate the value of a population parameter
When the goal is to estimate the proportion of successes in a single population, we use a one sample z ______
interval
Should always check for
- Data collected using a random sample from population
- When sampling w/out replacement, sample size is ≥ to 10% of the population
- Shape approximately normal; np^≥10 and n(1-p^)10
We don’t use p and use p^ instead because
we’re trying to figure out the truth about the population
the critical value of a 95% confidence interval is
1.960
For the interpretation of the confidence Interval
“We are __% confident that the interval from ___ to ___ captures the [parameter in context]” (must include all)
To get the margin of error in the calculator click: menu –>6; stats—>6; confidence intervals–>5; 1-prop z interval
Then number of successes, x and n, the total number of the random sample
What is C Level?
Confidence Level
We use the past tense in the conclusion because
we’re referring to the proportion and not the sample
The steps for constructing a confidence interval are…
- State: The parameter you want to estimate and the confidence level
- Plan: Identify the appropriate inference method (One-sample z (interval or test) for a proportion. Check conditions
- Do: If the conditions are met, do calculations :(
- Conclude: Interpret
To reduce the margin of error
More C Level like critical value
To interpret the C Level (Confidence level)
“If we were to select many random samples of the same size from the same population and construct a C% confidence interval using each sample, about C% of the intervals would capture the [parameter in context].”
To increase the margin of error
more sample size
