for charandry only
Choose any two classmates and review their main posts.
- Review the student’s response to numbers 1 and 2 above. Compare these answers to your answers. Create a paragraph that offers this comparison and better explains why samples can estimate population parameters, but will never be 100% accurate.
- Review the student’s responses to numbers 3 and 4. Evaluate their work and answer. What variable did they choose? What were their sample mean, sample standard deviation, and sample sizes? Is their margin of error E correct? If yes, what is their margin of error and what does it tell you? If not, correct it and show all the work and steps.
Student 1 post Deanna
- It is often impossible to know the actual value of any population parameters because populations are so large that we can’t possibly survey the whole population. One example I have been thinking of is- how many vegetarians there are in the U.S. To do this, we would have to survey each person in the U.S – which is impossible. Even on a smaller scale, another example is how many New Yorkers smoke. We would have to survey each New Yorker to find this value, and even though it is on a smaller scale to do this is impossible. Therefore, samples are so important.
- The sample size effects the estimate because depending on how the sample is pulled- it may alter the estimate. For the example of smokers in NY, by chance we could choose a sample who are all nonsmokers. This would be a false estimate because the sample does not represent the whole population.
- There will always be errors because the sample is just a small portion being taken from the population. The sample could easily be skewed to one way and not be accurate. Since populations could be very large – the sample could easily be taken from a certain area where the data will be the same and not varied. This will make the results un realistic. Therefore it is impossible to get 100% accuracy. If we wanted 100% accuracy we would need to survey the entire population not missing one part.
- Using grades- the average came to 80.65
Standard Deviation – 9.4
Margin of Error = 2(9.4) / sqrt(20) = 4.20
The 95% confidence interval ( 76.45,84.85)
Student 2 post Jola
1. It is often impossible to know the actual value of a population parameter because there will be almost no instance where you are able to get the data for the entire population. Two examples of this would be the mean height and weight of females ages 21-35. You are able to estimate this based on a sample of the population but it would be almost impossible to gather the date for the entire population of females 21-35.
2. When using samples to estimate your data, the greater the sample size the closer the results are to the true population. With smaller sample sizes you risk an inaccurate estimate to the true population mean.
3. When using a sample to estimate a population there will always be errors because there are always outliers in any population. Having outliers can impact the sample mean both positively and negatively so we take a margin of error to determine the confidence interval that we have for the sample. Again the greater the sample size the smaller our confidence interval will be (since to calculate the confidence interval you are dividing by the square root of the size of the sample).
4. Using the data set for random female weights[135,160,128,145,172,136,119,154,139,129,142,141,140,154,163,152,158,139,144,146]
I was able to calculate the mean using the excel formula to be 144.8 as well as the standard deviation using excel to be 12.9436. To calculate my margin of error I have:
E= 1.96*s / sqrt (n) = 1.96(12.9436) / sqrt (20) = 25.3695 / 4.4721 = 5.6728
Therefore the 95% confidence interval would be [139.1272, 150.4728]
Respond to the next student post in a paragraph
Unit 9 Discussion
Messages such as email or text is one of the biggest ambiguities used to communicate. I can think of a situation where I sent an email to one of my coworkers. The email was of a job posting, I was trying to send it to her as an FYI. The job posting would have been a promotion and a higher paying job for her. I was thinking the job would have been nice for her to try to apply. She thought since I sent her the job that I knew something about her getting the job. She had already applied and by me sending her the job she thought I was trying to tell her she got it.
When she approached me ready to celebrate I had to clarify. I had to tell her that I did not know she applied and I was sending her the job because I believed that she would be a good fit. It was a let down for her and I was very embarrassed.
The truth is, that email, and texts are lazy ways used to communicate these days, they leave every word that is written open for interpretation and confusion. The more messages that go back and forth the more the confusing the conversation can get and can escalate without that being the intent. The moral here is when there are too many messages going back and forth, a face to face may be a better option.
Working from home is the best thing happened to me, for now. I do not have to drive to work; I do not have a work schedule and no late meetings. However, sometimes the communication with the supervisors can be a real challenge. One of the requirements in my work is that the communication between the teamwork should be by email because of the difference in time zone. We start a new project every six months. When we are starting a new project, the supervisor sends the instructions along with the guidelines of the designated project.
In occasions, I have to deal with the discrepancy between the guidelines and the instructions, and in order to complete the work satisfactorily, we must follow both, the guidelines and the instructions. The communication by email can be a little slow, since the difference in time zone, In times, I have to stop the work for a day or so just waiting for an answer or approval. In my opinion, to communicate more effectively, the supervisors can set up a telephone call meeting with all the teamwork when a new project starts, so everyone can talk about possible doubts, or just talk about the expectations of the new projects so that everyone can be on the same page at the same time.