Biostatistic Homework

PBHL-B301 Homework #1                                                                            Name:  

Please note that many of these problems ask you to do two things – if you do only one, you can only be awarded half credit.

Don't use plagiarized sources. Get Your Custom Essay on
Biostatistic Homework
Get a plagiarism free paper Just from $13/Page
Order Essay
  1. (12 pts) Explain (1) what is wrong with each of the following randomization procedures and (2) describe how you would do the randomization correctly. You should use your notes and think about things like sampling bias, and proper randomization schemes we discussed in the notes and how to employ them.
    • Ten subjects are to be assigned to two treatments, 5 to each. For each subject, a coin is tossed. If the coin comes up heads, the subject is assigned to the first treatment; if the coin comes up tails, the subject is assigned to the second treatment.
    • Twenty students are to be used to evaluate a new treatment. Ten men are assigned to receive the treatment and 10 women are assigned to be the controls.
    • An experiment will assign 40 rats to 4 different treatment conditions. The rats arrive from the supplier in batches of 10 rats and the treatment lasts two weeks. The first batch of 10 rats is randomly assigned to one of the four treatments, and data for these rats are collected. After a one-week break, another batch of 10 rats arrives and is assigned to one of the three remaining treatments. The process continues until the last batch of rats is given the treatment that has not been assigned to the three previous batches.


  1. (12 pts) Explain (1) what is wrong with each of the following random selection procedures and (2) explain how you would do the random selection correctly. You need to use concepts from the notes, such as simple random sampling, stratified random sampling, to answer these questions.
    • A population of subjects is put in alphabetical order and a simple random sample of size 10 is taken by selecting the first 10 subjects in the list.
    • To determine the reading level of an introductory statistics text, you evaluate all the written material in the third chapter.
    • You want to sample student opinions about a proposed change in procedures for changing majors. You hand out questionnaires to 100 students as they arrive for class at 7:30am.


  1. (6 pts) Two drugs were tested to see whether they helped women who had breast cancer without lymph node involvement. The drugs are called TAC (docetaxel, doxorubicin, and cyclophosphamide) and FAC (fluorouracil, doxorubicin, and cyclophosphamide). About half of the 1060 women with breast cancer without lymph node involvement were randomly assigned to TAC and the other half were assigned to FAC. After 77 months, 472 out of 541 of the women assigned to TAC were alive and 425 out of 524 women assigned to FAC were alive (Source: Martin et al., Adjuvant docetaxel for high-risk, non-negative breast cancer, New England Journal of Medicine 363(23): 2200-2210)
    • Find the sample percentages of survival and compare them descriptively.
    • Was this an observational study or an experiment? Explain why. From studies like these, can we conclude a cause-and-effect relationship between the drug type and the survival percentage? Why or why not?



Download the data file HW1Data.xlsx from Canvas.  This file contains the first name and School of major for students in a certain class.

  1. (2 point)  Fill in the following table with the names and School of major (e.g. Medicine, Public Health, Nursing, Dentistry, Science, etc.) of five of your college friends or acquaintances.  These friends or acquaintances you fill in the table below can be students at IUPUI or any other university.


  1 2 3 4 5



  1. (2 points)  How many were Public Health students?  Find the proportion of Public Health students in your sample by taking =



  1. (3 points)  Is the collection of names in #4 a simple random sample (SRS) of college students in the US?  Why or why not?  Do you think there is any bias involved?  If so, how?  Do you think your own major has anything to do with the names that you collected?




For the remaining problems, we will assume that the 25 individuals in HW1Data.xlsx form a “population”. In truth, this is not the case, but we are doing this exercise to illustrate the concepts of sampling and sampling variability.

  1. (5 points) Open the attached Excel file, HW1Data.xlsx, and note the first column, “Student”, which will be the Student Number for selecting simple random samples (SRS’s).  For this problem, you will select SRS’s using the classic “drawing from a hat” method. Create 25 small slips of paper, all of fairly equal size. On these slips of paper, write numbers from 1 to 25 and then fold them in half. Next, put the 25 slips of paper into a hat, a bowl, or something else you can draw from. Finally mix up the paper slips and then hold the hat/bowl up above your eye level and randomly pull out 5 slips of paper.  Write down the names who were selected and the School for each student selected.  Put the slips back into the hat/bowl, mix them up again, and repeat this process for 4 more times, to complete 5 simple random samples (SRSs). Fill in the names and Schools for your 5 SRS’s below (on the next page):


SRS #1:

  1 2 3 4 5


SRS #2:

  1 2 3 4 5


SRS #3:

  1 2 3 4 5


SRS #4:

  1 2 3 4 5


SRS #5:

  1 2 3 4 5


  1. (4 points)  Find the sample proportion of Public Health students for each of your SRS’s using the method above from problem #5.  Enter your sample proportions below:


Sample proportions:

  SRS #1 SRS #2 SRS #3 SRS #4 SRS #5


Were all of the sample proportions in problem #8 the same?  Probably not.  Sample statistics will vary from sample to sample.  Our sample size is fairly small, so we have a lot of variability.  The larger the sample size, the smaller the sampling variability will be.  This will be an important fact that we will use all semester. 


  1. (4 points)  In most real life situations, we don’t know the population parameters.  However, looking at all the original data in the file HW1Data.xlsx, what is the true population proportion?


= ?



Within problems #7-8 above, how did your sample proportions from SRS #1 through SRS #5 compare to this population proportion?  Were they close?   A larger sample size will also give us more accurate results (sample statistics closer to the true population parameter).


Master Homework
Order Now And Get A 20% Discount!
Pages (550 words)
Approximate price: -

Advantages of using our writing services

Custom Writing From Scratch

All our custom papers are written by qualified writers according to your instructions, thus evading any case of plagiarism. Our team consists of native writers from the USA, Canada, and the Uk, making it convenient for us to find the best to handle your order.

Unlimited Free Revisions

If you feel your paper didn't meet all your requirements, we won't stop till it's perfect. You're entitled to request a free revision within 7 days after we submit your paper.

Quality Writing In Any Format

If you have issues with citing sources and referencing, you need not worry. Our writers are highly knowledgeable in referencing, including APA/MLA/Havard/Chicago/Turabian and all other formatting styles.

Fast Delivery And Adherence To The Deadline

All our custom papers are delivered on time, even the most urgent. If we need more time to perfect your paper, we may contact you via email or phone regarding the deadline extension.

Originality & Security

At Master Homework, your security and privacy is our greatest concern. For this reason, we never share your personal information with third parties. We use several writing tools to ensure your paper is original and free from plagiarism.

24/7 Customer Support

Our agents are online 24 hours a day, 7 days a week, and are always ready to serve you. Feel free to contact us through email or talk to our live agents whenever you need assistance with your order.

Try it now!

Calculate the price of your order

We'll send you the first draft for approval by at
Total price:

How it works?

Follow these simple steps to get your paper done

Place your order

Fill in the order form and provide all details of your assignment.

Proceed with the payment

Choose the payment system that suits you most.

Receive the final file

Once your paper is ready, we will email it to you.

Our Services

We work nonstop to see the best client experience.


Flexible Pricing

We offer pocket-friendly prices that coincide with the preferred client's deadline.


Admission help & Client-Writer Contact

Our support team is always ready to ensure vital interaction between you and the writer whenever you need to elaborate on something.


Paper Submission

We deliver our papers early within the stipulated deadlines. We are glad to help you if there should be an occurrence of any alterations required.


Customer Feedback

Your review, positive or negative, is of great concern to us and we take it very seriously. We are, consequently adjusting our policies to ensure the best customer/writer experience.