PBHL 5401 Lecture Notes - Lecture 24: Confidence Interval, Point Estimation, Standard Score

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mauvehamster904

9 Apr 2016

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This means you take the point estimate and + it to the margin of error. Then you take the point estimate and subtract it from the original margin of error giving you a confidence interval. Process of determining likely values for unknown population parameter, point estimate is best single-valued estimate for parameter, confidence interval is range of values for parameter. Confidence interval means our sample lies in between the interval. These values are very important, the problem will tell you which level of confidence you want to test for so you will use this z score. If the sample size is more than 30 use the z score. If a variable can take on any value between its minimum value and its maximum value, it is called a coninuous variable; We usually test for 95% interval so the alpha level ( )= 0. 05. If the same size is less than 30 use the t score.

Related Questions

(1)Agri-Beef Inc. operates cattle feedlots in several midwestern states. The company wishes to estimate the average daily weight gain of cattle on their lots. To do this a simple random sample of cattle is taken and the daily weight gain is recorded. The data below, in pounds, represent the results of the sample.

8.7

6.1

9.8

6.5

8.3

6.3

5.8

8.0

8.7

5.1

7.0

6.0

7.9

6.1

a. Construct a 95% confidence interval estimate for the true daily weight gain.
b. Construct a 99% confidence interval estimate for the true daily weight gain.
c. Discuss the differences between the two estimates found in parts a and b
and indicate the advantages and disadvantages of each.

(2)A survey of 400 women for the American Orthopedic Foot and Ankle Society revealed that 38% wear flats to work.

a. Use this sample information to develop a 99% confidence interval for the population proportion of women who wear flats to work.

b. Suppose the society wished to estimate the proportion of women who wear athletic shoes to work and the proportion of women who wear flats to work within a margin of error of 0.01 (one percentage point) with 95% confidence. Determine the sample size required.

whitekangaroo461

The USA Today reports that the average expenditure on Valentine's Day is $100.89.Do male and female consumers differ in the amounts they spend? The average expenditure in a sample survey of 30 female consumers was $68.64, and the average expenditure in a sample survey of 40 male consumers was 135.67. Based on past surveys, the standard deviation for male consumers is assumed to be $35, and the standard deviation for female consumers is assumed to be $20.

a. What is the point estimate of the difference between the population mean expenditure for males and the population mean expenditure for females?

b.At 99% confidence, what is the Margin of Error?

c.Develop a 99%confidence interval for the difference between two population means.

lavendermule614

6. As the test statistic becomes larger, the p-value

(a) gets smaller

(b) becomes larger

(d) becomes negative.

7. To describe the sampling distribution of the sample proportion, we use

(a) The sample proportion

(b) The population proportion

(d) The population mean

8. When small samples are used to estimate a population mean, in cases where the population standard deviation is unknown and the original distribution is normal:

(a) There always will be a large amount of sampling error.

(b) the t-distribution must be used to obtain the critical value.

(d) the z distribution must be used to obtain the critical value.

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PBHL 5401 Lecture Notes - Lecture 24: Confidence Interval, Point Estimation, Standard Score

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