Joseph: Health insurance premiums are growing at an alarming rate.

Joseph and Ronald are generally in agreement over the exorbitant health care cost. (The state of healthcare in US is indeed in turmoil. Insurances and practitioners are driven by avarice. )

For Joseph, its assumption is: Tests and diagnostic procedures do not make up an insignificant portion of the bills that are sent to insurers.

From "unnecessary diagnostics and tests are partially responsible for uncontrollable premium growth", we cannot confidently conclude that "reducing the number of unnecessary tests performed by health care providers will be effective in controlling growing health insurance premiums" unless "tests and diagnostic procedures do not make up an insignificant portion of the bills that are sent to insurers."

"Doctors are generally able to determine, with great reliability, which diagnostic procedures and tests would yield the most effective results" is attractive but not essential. Joseph's conclusion does not suggest that doctors will be tasked to determine the unnecessary tests. Maybe insurance can decide, or patients, or AI (artificial intelligence). Negating this statement won't render the conclusion wrong.

For "Ronald", the assumption is "Patients are not just as likely as doctors to choose the most expensive diagnostics and tests." This is relatively straightforward.

The key to assumption question is to identify the conclusion. For Ronald, the conclusion is "in order to succeed in reducing the number of unnecessary tests, we should allow the patients to decide which course of diagnostics they would like to undergo". If patients are just as likely to choose the most expensive tests, the conclusion thoroughly collapses.

Joseph - Insurance companies in other industries, such as auto and home, have been able to reduce costs by reducing the
number of unnecessary repairs and replacements on claims for automobiles and homes.

Ronald - Patients are not just as likely as doctors to choose the most expensive diagnostics and tests.

Since we have to identify the assumptions, let's find out the conclusions of the arguments.

If we look at Joseph's argument, we can see that there is a conclusion marker "Therefore" in the last sentence.

Joseph's conclusion: Reducing the number of unnecessary tests performed by health care providers will be effective in controlling growing health insurance premiums.

If we look at Ronald's argument, we can see that there is a conclusion marker "As a result" in the last sentence.

Ronald's conclusion: we should allow the patients to decide which course of diagnostics they would like to undergo.

Option 1: Doctors are generally able to determine, with great reliability, which diagnostic procedures and tests would yield the most effective results.

This statement has no effect on Joseph's argument. Doctors are generally capable of determining which test would yield the most effective result. This does not mean that doctors are going to not suggest unnecessary tests. We don't know. (Any Docs reading this, I love you, you are the best )

This statement straight away weakens Ronald's conclusion. If the doctors are able to determine the procedures and tests with great reliability, then why should the patient decide.

Option 2: Tests and diagnostic procedures do not make up an insignificant portion of the bills that are sent to insurers.

This is an assumption that Joseph has to make. If we negate this statement, the statement would be "Tests and diagnostic procedures do make up an insignificant portion of the bills that are sent to insurers." If they are an insignificant portion of the bills, then even if they are included (or not included), there is no value. So, it is important to assume that tests and diagnostic procedures make up a significant portion of the bills.
(do not make up an insignificant portion = make up a significant portion)

Option 3: Insurance companies in other industries, such as auto and home, have been able to reduce costs by reducing the number of unnecessary repairs and replacements on claims for automobiles and homes.

This statement does not affect both options. What happens in Insurance companies cannot be compared with what happens with doctors. When we are comparing 2 items, we have to make sure that the differences between those 2 items are very very minimal. If the differences are huge, n number of items can go right or wrong.

Option 4: Patients are not just as likely as doctors to choose the most expensive diagnostics and tests.

This is an assumption that Ronald has to make. If we negate this statement, the statement would be "Patients are just as likely as doctors to choose the most expensive diagnostics and tests." This is weakening Ronald's argument. If the patients are also deciding like doctors, then there is no point in allowing patients to decide the course of diagnostics. So, it is important for Ronald to assume that the patients do not decide as to how doctors decide.

Option 5 Health insurance premiums have increased twice as fast in the past five years than they have over an average of the past 25 years.

This does not have any effect on both statements. Whatever happened in the past five years is not giving any valid information.

Answer
Joseph: Option 2
Ronald: Option 4
_________________

1. Doctors are generally able to determine, with great reliability, which diagnostic procedures and tests would yield the most effective results.
2. Tests and diagnostic procedures do not make up an insignificant portion of the bills that are sent to insurers. - Joseph's Assumption
3. Insurance companies in other industries, such as auto and home, have been able to reduce costs by reducing the number of unnecessary repairs and replacements on claims for automobiles and homes.
4. Patients are not just as likely as doctors to choose the most expensive diagnostics and tests. - Ronald's Assumption
5. Health insurance premiums have increased twice as fast in the past five years than they have over an average of the past 25 years.

Competition mode on this question is off now!

OA is posted, It is:

Joseph: Tests and diagnostic procedures do not make up an insignificant portion of the bills that are sent to insurers.
Ronald: Patients are not just as likely as doctors to choose the most expensive diagnostics and tests.

Good job is done by both zhanbo and Sr1994

No explanation is provided by sshwetima

Thank you!