How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Chris M. Your Own Question

Chris M.
Chris M., M.S.W. Social Work
Category: Homework
Satisfied Customers: 2514
Experience:  Master's Degree, strong math and writing skills, experience in one-on-one tutoring (college English)
22285537
Type Your Homework Question Here...
Chris M. is online now
A new question is answered every 9 seconds

can you please answer these questions for me thanks Sensitivity/Specificity

Resolved Question:

can you please answer these questions for me?
thanks


Sensitivity/Specificity Problem Set.

Clearly mark your responses for each question.



1) Sensitivity is:
A. The probability that a test correctly classifies as positive those who have preclinical disease.
B. The probability that a test correctly classifies individuals without preclinical disease as negative
C. The probability that those who test positive have the preclinical disease
D. The probability that those who test negative do not have the preclinical disease

2) Specificity is:
A. The probability that a test correctly classifies as positive those who have preclinical disease.
B. The probability that a test correctly classifies individuals without preclinical disease as negative
C. The probability that those who test positive have the preclinical disease
D. The probability that those who test negative do not have the preclinical disease

A screening examination was performed on 250 persons for Factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted below:

RESULTS OF DIAGNOSIS
TEST RESULTS Disease Y Present Disease Y Absent
Positive for Factor X 40 60
Negative for Factor X 10 140

3) The sensitivity of this test is expressed as:
A. 40%
B. 70%
C. 29%
D. 80%


4) The specificity of this test is expressed as:
A. 40%
B. 70%
C. 7%
D. 80%

5) The positive predictive value of this test is:
A. 40%
B. 70%
C. 7%
D. 80%

6) The negative predictive value of this test is:
A. 40%
B. 70%
C. 93%
D. 80%

7) If the same screening test is conducted in two populations, one with a high prevalence of the disease and one with a low prevalence of the disease, assuming the sensitivity and specificity of the screening test are the same, which of the following statements about positive predictive value (PPV) applies:

A. PPV is higher in the screened population with higher prevalence
B. PPV is lower in the screened population with higher prevalence
C. PPV is the same in both populations
D. It cannot be determined

8) Lead time bias can be described as:
A. An apparently lower survival rate among persons screened compared to an unscreened group.
B. A bias that occurs because screening tends to identify cases with less aggressive forms of the disease
C. A similar survival time for persons identified during a screening program relative to persons who are diagnosed by clinical symptoms.
D. An apparently longer survival time among those identified during a screening program because they were identified at an earlier stage of their disease

9) Length-Bias can be described as:
A. An apparently lower survival rate among persons screened compared to an unscreened group.
B. A bias that occurs because screening tends to identify cases with less aggressive forms of the disease
C. A similar survival time for persons identified during a screening program relative to persons who are diagnosed by clinical symptoms.
D. An apparently longer survival time among those identified during a screening program because they were identified at an earlier stage of their disease


A new screening test for a disease is developed for use in the general population. The sensitivity and specificity of the new test are 60% and 70%, respectively. Four hundred (400) people are screened at a clinic during the first year the new test is implemented. (Assume the true prevalence of the disease among clinic attendees is 10%.)
Calculate the following values:

10) The predictive value of a positive test is:
A. 13.3%
B. 18.2%
C. 24%
D. 22.2%


11) The number of false positives is:
A. 108
B. 132
C. 24
D. 252
Submitted: 3 years ago.
Category: Homework
Expert:  Chris M. replied 3 years ago.
THIS ANSWER IS LOCKED!
You can view this answer by clicking here to Register or Login and paying $3.
If you've already paid for this answer, simply Login.
Chris M., M.S.W. Social Work
Category: Homework
Satisfied Customers: 2514
Experience: Master's Degree, strong math and writing skills, experience in one-on-one tutoring (college English)
Chris M. and 10 other Homework Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
< Last | Next >
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
  • He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here. Diane Dallas, TX
 
 
 

Meet The Experts:

 
 
 
  • Manal Elkhoshkhany

    Tutor

    Satisfied Customers:

    4522
    More than 5000 online tutoring sessions.
< Last | Next >
  • http://ww2.justanswer.com/uploads/BU/BusinessTutor/2012-2-2_115741_Kouki2.64x64.jpg Manal Elkhoshkhany's Avatar

    Manal Elkhoshkhany

    Tutor

    Satisfied Customers:

    4522
    More than 5000 online tutoring sessions.
  • http://ww2.justanswer.com/uploads/ComputersGuru/2010-02-13_051118_Photo41.JPG LogicPro's Avatar

    LogicPro

    Engineer

    Satisfied Customers:

    3458
    Expert in Java C++ C C# VB Javascript Design SQL HTML
  • http://ww2.justanswer.com/uploads/LI/lindaus/2012-6-10_04811_IMG20120609164157.64x64.jpg Linda_us's Avatar

    Linda_us

    Finance, Accounts & Homework Tutor

    Satisfied Customers:

    3124
    Post Graduate Diploma in Management (MBA)
  • http://ww2.justanswer.com/uploads/chooser77/2009-08-18_162025_Chris.jpg Chris M.'s Avatar

    Chris M.

    M.S.W. Social Work

    Satisfied Customers:

    2385
    Master's Degree, strong math and writing skills, experience in one-on-one tutoring (college English)
  • http://ww2.justanswer.com/uploads/JawaadAhmed/2009-6-27_12137_SIs_SHadi.jpg F. Naz's Avatar

    F. Naz

    Chartered Accountant

    Satisfied Customers:

    1988
    Experience with chartered accountancy
  • http://ww2.justanswer.com/uploads/JK/jkcpa/2011-1-16_182614_jkcpa.64x64.jpg Bizhelp's Avatar

    Bizhelp

    CPA

    Satisfied Customers:

    1876
    Bachelors Degree and CPA with Accounting work experience
  • http://ww2.justanswer.com/uploads/avremote/photoa.jpg Seanna's Avatar

    Seanna

    Tutor

    Satisfied Customers:

    1781
    3,000+ satisfied customers, all topics, A+ work
 
 
 

Related Homework Questions