Chapter 9 - Estimation and Confidence Intervals

Question 1

What is statistics?

Answer 1

The science of collecting, organizing, presenting, analyzing, and interpreting data to assist in making more effective decisions.

Question 2

reasons for sampling

Answer 2

• contacting the entire population is too time consuming
• studying all the items in the population is often too expensive
• the sample results are usually adequate
• certain tests are destructive
• checking all the items is physically impossible

Question 3

most widely used sampling method is ____.

Answer 3

simple random sampling

Question 4

____ are methods of sampling.

Answer 4

systematic, stratified, cluster, simple

Question 5

median

Answer 5

the value of the middle observation after all the observations have been arranged from low to high. For example, if observations 6,9,4 are rearranged to read 4,6,9, the median is 6, the middle value.

Question 6

midpoint

Answer 6

the value that divides a class into tow equal parts. For the classes $10 up to $20 and $20 up to $30, the midpoints are $15 and $25, respectively.

Question 7

mode

Answer 7

the value that appears most frequently in a set of data. For grouped data, it is the midpoint of the class counting the largest number of values.

Question 8

point estimates

Answer 8

a single value (point) derived from sample information and used to estimate a population parameter. Ex. on pg 280

Question 9

confidence interval

Answer 9

A range of values constructed from sample data so that the population parameter is likely to occur within that range at a specific probability. The specific probability is called the level of confidence.

Question 10

A confidence interval is computed using ____.

Answer 10

the sample mean and the standard deviation

Question 11

The standard deviation measures the _____ of a population or sample distribution.

Answer 11

dispersion, or variation

Question 12

In computing a confidence interval, the ______ is used to compute the limits of the confidence interval.

Answer 12

standard deviation

Question 13

standard deviation

Answer 13

the square root of the variance

Question 14

standard error of estimate

Answer 14

measures the dispersion of the actual y values about the regression line. It is reported in the same units as the dependent variable.

Question 15

The width of the interval is determined by _______.

Answer 15

(1) the level of confidence

(2) the size of the standard error of the mean.

Question 16

The size of the standard error is affected by ____.

Answer 16

(1) the standard deviation of the population.

(2) the number of observations in the sample.

Question 17

A large number of _____ in the sample will result in a small standard error of estimate, indicating that there is _____ in the sample means.

Answer 17

observations; less variability

Question 18

sampling error

Answer 18

the difference between a sample statistic and the corresponding population parameter. Example: The sample mean income is $22,100; the population mean is $22,000. The sampling error is $22,100 - $22,000 = $100. This error can be attributed to sampling- that is , chance.

Question 19

economics

Answer 19

of or relating the development, production of wealth