Question

A positive predictive value (PPV) of 0.70 for a lung cancer test means that

A. If the person has lung cancer, they are 70% sure that they have it |
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B. If the person tests positive, they have a 70% chance of having lung cancer. |
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C. If the person has lung cancer, they have a 70% chance of testing positive. |
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D. If the person has brain cancer, they have a 70% chance of testing positive. |

Answer #1

TOPIC:Positive predictive value(PPV).

Prostate-specific antigen (PSA) test is a common screening test
used for detecting prostate cancer. From Harvard Medical School
“Prostate Knowledge” webpage.
Is PSA
reliable?
Although PSA
testing can help catch prostate cancer at an early stage, having an
elevated PSA (generally considered more than 4 ng/ml) doesn’t
necessarily mean that a man has cancer. Noncancerous conditions,
including benign prostatic hyperplasia (BPH), or an enlarged
prostate, and prostatitis, can raise PSA levels. In fact, studies
have shown that about 75% of...

Suppose a particular woman tests positive; what is the
probability that she has breast cancer?
To pin this question , please consider a population in which 1%
of women have breast cancer, and a mammography test which has a 90%
chance of returning a correct result. That is, if a woman has
cancer then there is a 90% chance the test will be positive, and if
a woman does not have cancer then there is a 90% chance the test...

We want to figure out if lung cancer is related to
smoking or not. Suppose that we know 0.3 % of the people has lung
cancer and 85% of the people with lung cancer were a current or
previous smoker. Also we know that 25% of the people who do not
have lung cancer, smoke. With these information, answer the
following parts: (5 points each)
a) what is the probability of having lung cancer in
non-smokers?
b) What is the...

Suppose that a screening test for breast cancer has 95%
sensitivity and 90% specificity. Assume 1% of the population being
screened truly has breast cancer.
a. If you really do have breast cancer, what is the probability
that the test says you do?
b. If you really do not have breast cancer, what is the
probability that the test says you do?
c. The screening test is applied to a total of 15 people; 5 who
really do have cancer...

A test for ovarian cancer has a 2% rate of false positives (i.e.
2% of women who don’t actually have ovarian cancer test positive)
and a 0% rate of false negatives. Data collected by the
Cancer association estimates that 1 in every 2500 women over 35
years of age having ovarian cancer. Answer the following questions.
[All numeric answers should be accurate to 6 decimal
places]
What is the probability that a randomly selected woman over the
age of 35...

5. In medical tests the prevalence of a disease in a given
population is the percentage of the population that has the
disease. For a population with a known prevalence, the positive
predictive value (PPV) of a test is the probability that a person
in the population that tests positive actually has the disease. The
negative predictive value (NPV) of a test is the probability that a
person in the population who tests negative, in fact, does not have
the...

A person takes a test to detect the occurence of a disease. The
test’s characteristics are such that a person testing positive has
actually a 70% chance actually having contracted the disease.
Meaning that a person not having contracted the disease has a 30%
chance of testing positive to it.
The test’s results are used to allow a person to exit a
quarantine – because having the disease makes them immune to it and
they are no longer in risk...

Mammograms are a relatively inexpensive and nonintrusive way to
test for breast cancer. Suppose that mammogram screenings are 93%
specific and 87% sensitive. This means that those without breast
cancer test negative 93% of the time and those with breast cancer
test positive 87% of the time. Answer the following questions as if
12.6% of all women have breast cancer.
a) Given that a women tests negative, what is the probability
that she has breast cancer?
(b) Given that a...

The prevalence of a disease D among the population is 3%. There
is a diagnostic test for disease D. The sensitivity of this test is
99%, this means that the test is positive given that the person has
the disease. The specificity of this test is 98%, this means that
the test is negative given that the person does not have the
disease.
a) Given that a person tests positive, what is the probability
that the person does not have...

"To diagnose colorectal cancer, the hemoccult test is
conducted to detect occult
blood in the stool. For symptom-free people over 50 years old who
participate in
screening using the hemoccult test, the following information is
available.
The probability that one of these people has colorectal cancer is
0.3 percent. If a
person has colorectal cancer, the probability is 50 percent that he
will have a
positive hemoccult test. If a person does not have colorectal
cancer, the
probability is 3...

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