Confidence Intervales

CONFIDENCE INTERVALS

A tool that allow to capture the sample measure of a population.

The Data

is

parts

The Math

The Interpretation

Those allow to capture a "true" measure of a population.

Working with sample data, allow to apply a confidence interval .

Sampling Bias

Means a certain group has been under- or over- represented in a sample.

subsets

The sample does not represent the entire population.

Statistic vs Parameter

Statistic describes a Sample.

Parameter describes a Population.

It´s used to estimate parameters

No know the details of an entire population.

a t or z value derived from the confidence level, and the standard error.

Ex. sample mean

Piece that is added to and subtracted from the statistic to build the entire interval.

Estimate of the true parameter.

Defines the width of an interval.

main components

The purpose is to narrow down our search for the population parameter.

Confidence Level

Standard Error

Theoretical distribution of all possible sample means.

larger sample size(n) will reduce the width of the margin of error without sacrificing the level of confidence.

analysis

Interval

Level

Analysis of the results obtained from the sample

Probability that the interval obtained from the sample contains the truel population mean.

Visualizing the Confidence Interval

The confidence level does not imply the probability the parameter is contained in the interval

The resulting intervals will contain the mean C% of the time

C is your confidence level.

Statistic

Margin of error