Exam 3 - Statistical Inference

Question 0

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.

Answer 0

Sample….unknown population parameter…confident

Question 1

Statistical inference provides

Answer 1

Methods for drawing conclusion about population from sample data

Question 2

Confidence interval has two parts

Answer 2

An interval calculated from the data and a confidence level

Question 3

Confidence interval often has a form:

Answer 3

Estimate +|- margin of error

Question 4

Probability

Answer 4

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

Question 5

Parameter

Answer 5

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

Question 6

Sampling distribution

Answer 6

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

Question 7

Statistic

Answer 7

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

Question 8

Simple conditions for inference about mean

1. We have ….
2. The variable we measure…
3. We don’t know the ….

Answer 8

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

Question 9

Non response

Answer 9

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

Question 10

Statistical inference

Answer 10

Drawing conclusion about a population parameter from a sample statistic

Question 11

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

Answer 11

Differs

Question 12

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

Answer 12

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

Question 13

Sampling distribution of x-bar provides

Answer 13

• probabilities on x-bar

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

Question 14

Margin of error

Answer 14

Is an estimate of the maximum size of the error

Question 15

What is used to estimate the value of parameter?

Answer 15

A confidence interval

Question 16

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

Answer 16

A test of significance

Question 17

T/F All inferential procedures have conditions

Answer 17

True

Question 18

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

Answer 18

False

Question 19

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

Answer 19

True This is the most important requirement for valid statistical inference

Question 20

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

Answer 20

To check for outliers which negate Normality

Question 21

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

Answer 21

True