EDLD 618 Chapter 11

EDLD 618 Chapter 11

Point and Interval Estimation

• set limits regarding the containment for the population parameter

• have a goal of learning more about the value of a mean or mean difference

Multiple Choice

In point and interval estimation, a goal is to make a decision regarding a null hypothesis.

• True

• False

False

The goal is to estimate the value of the population mean, not make a decision about it.

Point estimation

uses a sample statistic to estimate a population parameter.

Interval estimation (confidence interval)

the interval or range of values within which an unknown population mean is likely to be contained

Interval estimate or confidence intervals are reported as a point estimate

 $\pm$  an interval estimate.

They are stated with a level of confidence which defines the probability or likliehood a parameter is contained in the interval.

To compute and interpret confidence intervals...

• Compute the sample mean and standard error

• Choose the level of confidence and find the critical values

• Compute the estimation formula to find the confidence limits

Fill in the Blanks

What are the upper and lower limits of a 95% confidence level in the estimation formula 12 $\pm$   2.3

Multiple Choice

If a sample size is increased the precision of a confidence interval will...

• increase

• decrease

• not change

Increasing the sample size increases the precision of the confidence level

• The more observations that you have, the narrower the interval around the sample statistic. Often the researcher weighs the benefits of this as increasing sample size may not be practical.

Multiple Select

Another way to increase precision in the confidence interval would be...(check all that apply)

• reduce variability

• use effect testing

• lower the confidence level

Lowering the confidence level...

The advantage is an increase in precision, but the disadvantage is that you have less confidence that the confidence interval contains the population parameter you are interested in-.

Example - Lowering a 95% CI to 90% CI

Multiple Choice

If the null hypothesis is outside of the confidence interval, the researcher should ________ the null hypothesis.

• retain

• reject

Multiple Choice

A researcher compared the time in seconds that children in two classrooms remained seated during a behavioral task. The null is that the two classrooms will not differ. She reports a 95% CI = -2.1 to 32.6 seconds. What would the decision have been for a hypothesis test?

• reject the null

• retain the null