Exam 3 - Statistical Inference Flashcards Preview

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Flashcards in Exam 3 - Statistical Inference Deck (22):
0

Statistical inference provides

Methods for drawing conclusion about population from sample data

1

Confidence interval uses .... data to estimate .... with an indication of how accurate the estimate is and of how ... we are that the result is correct.

Sample....unknown population parameter...confident

2

Confidence interval has two parts

An interval calculated from the data and a confidence level

3

Confidence interval often has a form:

Estimate +|- margin of error

4

Probability

Proportion of times an outcome of a random phenomenon occur in a very long series of repetitions

5

Parameter

A number that describes the population. In stat practice, the value is unknown because we cannot examine the entire population

6

Sampling distribution

The distribution of values taken by a statistic in all possible samples of the same size from the same population

7

Statistic

A number that can be computed from the sample data without making use of any unknown parameters. In practice, we often use this to estimate an unknown parameter

8

Simple conditions for inference about mean
1. We have ....
2. The variable we measure...
3. We don't know the ....

1. An SRS from population of interest. There is non non response or other practical difficulty
2. Has an exactly Normal distribution mu, sigma in the population
3. Population mean mu but we do know popul stand dev sigma

9

Non response

When individual chosen for sample can't be contacted of refuses to participate

10

Statistical inference

Drawing conclusion about a population parameter from a sample statistic

11

Because of sampling variability: the sample statistic usually... From the population parameter

Differs

12

Sampling distribution of x-bar provides info for predicting the expected

Maximum difference between the sample statistic, x-bar, and the population parameter, mu

13

Sampling distribution of x-bar provides

- probabilities on x-bar
- a measure of variability of x-bar with the standard deviation of the sampling distribution of x-bar

14

Margin of error

Is an estimate of the maximum size of the error

15

What is used to estimate the value of parameter?

A confidence interval

16

What is used to assess evidence for or against a claim about a parameter value ?

A test of significance

17

T/F All inferential procedures have conditions

True

18

T/F some inferential procedures have conditions that must be, but others do not

False

19

T/F all inferential procedures always require properly collected data for the results to be valid

True This is the most important requirement for valid statistical inference

20

Why should we always plot our data before performing an inferential procedure?

To check for outliers which negate Normality

21

T/F In practice, since we seldom know the value of sigma, we use s to estimate sigma

True