Search Our Essay Database

Essay Instructions: Explain the concept of standard deviation in plain language. What is the purpose of this
statistics? What does it tell us? Also, to the best of your ability, explain each of the
terms in the standard deviation formula, and their purpose. For example, why is the
mean subtracted from each data point? Why are these difference scores summed, and
then squared, and then divided by N-1? Why is the final value square rooted? Give an example.

Essay Instructions: Research 1 peer-reviewed article on the topic, "standard deviation use in the business world" in the University Library.

Write a basic abstract for each of your selected articles. Your abstracts must include the following:

The purpose of the study
The research question(s)
The hypothesis of the study
The main findings of the study

Include APA-formatted references on the reference page.


Format your assignment consistent with APA guidelines.

Essay Instructions: Please make sure to show all work for each problem requiring calculations. Please highlight final answer. see attached word DOC.

What is the level of measurement for each of the following:

Final grades in this class ______________________

Weights of newborn babies ______________________

Seasons of the year ______________________

Boiling temperatures of different liquids ______________________

Types of sampling used:

I collect data from my class _______________________

Data from every fourth patient in the hospital _______________________

Data from 400 randomly selected students from those majoring in business, 763 randomly selected students from those majoring in education, and 392 randomly selected students from those majoring in criminal justice. _________________

Data from 4230 adults after phone numbers were randomly generated ________

The following data were collected on amounts of lawn debris after the major storm this past summer:

Pounds Frequency
2-5 2
6-9 2
10-13 6
14-17 15

What is the class width? ________________________

What are the class midpoints? ________________________

What are the class boundaries? ________________________

Create a histogram

The weekly salaries for teachers of different grade levels at my school are as follows:

774 649 1210 546 431 612


Do the different grades have much variation in salary? Base your decision on the calculated standard which needs to be part of your solution.

I counted the number of words on each posting from my Class Announcements and found the following:

128 130 133 137 138 142 142 144 147 149

151 151 151 155 156 161 163 163 166 172

What is the 5-number summary?


Construct a boxplot.


A study compared cognitive behavioral therapy (CBT) and regular talk therapy for patients with anxiety. It was found that among 73 patients treated with CBT, there was a 92% success rate. Among 83 patients treated with regular talk therapy, there was a 72% success rate. Calculations using these results showed if there really is no different in success rates between CBT and regular talk therapy, then there is about a one chance in 1000 (1/1000) of getting success rates like these.

Should we conclude that CBT is better than regular talk therapy for anxiety?

Does the result have statistical significance? Why or why not?

Does the result have practical significance? Why or why not?

Should we recommend CBT for treatment of anxiety?



(2 points) My cousin was 38 when she retired from the military. Most people who retire have a mean age of 43.8 years. The standard deviation is 8.9 years.

What is the difference between my cousin’s age and the mean age?

How many standard deviations is that (difference found in part a)?

Convert my cousin’s age to a z-score

If we consider “usual” age to be those that convert to a z score between -2 and +2, is my cousin’s age usual or unusual?


A survey was conducted asking people if they thought they were overweight. Participants were randomly selected. Data were analyzed by how many participants in each age group were male or female.

Age
18 ??" 21 22 ??" 29 30 ??" 39 40 ??" 49 50 ??" 59 60 +
Female 73 255 245 136 138 202
Male 11 20 33 16 27 49

What is the probability that the randomly selected participant is someone 60 or over and is female?

I’m not interested in males or in participants under 22 years of age or over 59 years of age. What is the probability that the randomly selected person is someone I’m not interested in?

Psychologists frequently measure achievement using a test with scores that are normally distributed, with a mean of 100 and a standard deviation of 15.

What is the probability that a child I test has an achievement score >131.5?

What is the probability that a child I test has an achievement score between 110 and 120?

What is the achievement score separating the bottom 37% from the others?

A plant in DC manufactures 400 calculators, of which 3 are defective. The Chicago plant of the same company manufactures 800 calculators, of which 2 are defective. If one of the 1200 calculators is randomly selected and is found to be defective, what is the probability that it was manufactured in DC?


Twenty students are eligible for a GT/LD program in my school district. A simple random sample of five is selected.

How many different simple random selections are possible?

What is the probability of each simple random sample?

In a study of families with children with disabilities, groups of 6 US households were randomly selected. In the table below, the random variable x represents the number of households among 6 that had a child with a disability living there.

x P(x)
0 0.539
1 0.351
2 0.095
3 0.014
4 0.001
5 0+
6 0+

What is the mean?

What is the standard deviation?

Is this a probability distribution? Why or why not?


A dental company my son works for makes implants so accurately that there is a 1/2000 probability of getting a defective implant. My dentist ordered 5 implants and claimed 2 of them were defective.

Find the probability of getting exactly 2 defective implants when buying 5 implants.

Find the probability of getting at least 2 defective implants when buying 5 implants.

Does my dentist’s claim of getting 2 defective implants seem valid? Explain.


A large number of simple random samples of n = 85 are obtained from a large population of birth weights having a mean of 3420 g and a standard deviation of 495 g. The sample x ? is calculated for each sample.

What is the approximate shape of the distribution of the sample means?

What is the expected mean of the sample means?

What is the expected standard deviation of the sample means?

Essay Instructions: Measures of Central Tendency and Dispersion with SPSS
The statistics for this week become the basis for several other tests you may do. These are the foundational concepts of statistics.
To prepare for this Application:
? Review Chapter 15 and Appendix E in the course text Research Methods in the Social Sciences. (Faxed Resource Material)
? Review the video programs for this week, located in the Learning Resources. (Transcripts in Resource Files)
? Review Lessons 19 and 21 in the course text Using SPSS for Windows and Macintosh: Analyzing and Understanding Data.(Faxed Resource Material)
? Select one of the data sets from the GSS data disk to use for this Application. (You will need to locate this disk. It is available inside the textbook "Research Methods in the Social Sciences" 7th Edition. YOU MUST HAVE THIS
? Select one variable that is measured as a continuous variable (age, Likert scale item, etc.) and one that is measured on a nominal scale (marital status, ethnicity, etc.).
The assignment: You will need to use the Finalroundvalley data set (Resource Files)
Using the data set mentioned above the variables you will analyze are gender, marital status, ethnicity, 3rd grade reading, and 9th grade first semester GPA. Pick any one categorical variable and any one interval variable and use SPSS to calculate the following:
o Mean
o Median
o Mode
o Range
o Minimum
o Maximum
o Standard deviation
o Very important ? keep in mind that you do not report all 7 of these for every scaled variable. See reference guide to statistics in doc sharing for what to report for different scaled variables.
? Generate syntax and output files in SPSS. You will need to copy and paste these into your Application document.
? Use one kind of chart (any kind) to describe the data for both 1 categorical variable and 1 interval variable ? hence you will have 2 total (1 for each type of variable.
? Based on your SPSS analysis, craft a 2- to 3-page report of the results using correct APA format. Your report should include:
o SPSS syntax and output files 2 charts as discussed above.
IBM SPSS Statistics will be necessary for this assignment.