I am trying to make a point of certain research areas are still in its young stage and is not ready to be widely used. What are some better way to express this?

# Tag: formally

## How do I formally test outliers from a linear regression?

Hello (and thanks for reading this).

I have a set of data that looks at the area of remaining retina against age. I have three points of data per patient. We know that over time, the area of remaining retina decreases exponentially. I have done a linear regression to model loss of area over time (see graph). X axis = age, Y axis = retinal area (log scale).

In this data there are some patients that are outliers because of their genetic mutation. I am interested in doing a formal test to see whether because of this mutation, they have a significantly larger area of retina remaining for their age, compared to the rest of the cohort. I have read about various tests (Grubbs, Dixon etc) but they don’t seem to apply here for bivariate data. I am aware that I can identify outliers by visualising them, but I want a formal test with a p value if possible to satisfy reviewers who have requested it.

Please see the attached graph to demonstrate what the data looks like. The red and green dots are the patients I am interested in testing. Any suggestions on how to analyse this would be most appreciated. I am using Prism 7 for analysis. I can’t seem to find an answer for this question on stack anywhere. As you can probably tell, my stats experience is fairly limited. Thanks for your help.

Age vs Area of retina (mm2)

## Can an argument be formally valid with sound premises and still be informally fallacious?

Consider the following two assumptions:

*Validity Assumption*: Assume an argument is valid. It follows all the formal logical rules of inference. The inference contains no formal logical fallacy.*Soundness Assumption*: Assume the premises of the argument are sound, verified by a competent subject-matter expert.

Given the soundness assumption, the validity assumption would imply that the conclusion is logically true.

Is it possible for this argument to still be an example of an *informal* fallacy?

What makes me think this is possible is that establishing the soundness assumption, which I *assumed* to be true, cannot be done with absolute certainty. The subject-matter expert verifying the premises as true may have made an error of judgment. The validity assumption is more reliable as an assumption than the assumption of soundness since it can be checked with a computer without involving human judgment.

This would make the list of informal logical fallacies valuable. They would be ways to test sound and valid arguments by identifying places where the argument could go wrong.

What I am looking for are examples of such situations that would answer the question in the title as “yes” or an argument that such examples are not possible.

To repeat the question: *Can an argument be formally valid with sound premises and still be informally fallacious?*

## Using functions in formally well defined statements

Given a function $AnyS(n)$ that returns an undefined number of sets with $n$ different aleatory integers, and the function $Min(S)$ that returns the minimun integer of a set of integers, and the function $Avg(S)$ that retuns the most close member of a set of integers to the average of its members.

Is this statement formally well defined? Must be functions declared before?

$$forall R in (forall S in AnyS(9)) implies Min(R) neq Avg(R)$$

## Formally prove that $lim(frac{2n}{n+1})=2$

Taking Real Analysis for the first time and having trouble grasping what i need to show for the proof. I know i need for any $epsilon > 0$, there exists a positive integer $N$, such that if $n geq N$, then $$biggl|frac{2n}{n+1}-2biggr|= frac{2n}{n+1} < epsilon $$

I’m not sure where to go from here. Do I need to solve for $n$ on the right hand side?

## How would formally ask someone to confirm return date to book a ticket

I would like to book a return ticket back to my hometown for a particular date. I need to ask my someone before finalizing the date. How can I express that in a question form? I have few examples:

- (For) which date/day should I book my return ticket?
- When should I return?
- I am thinking of returning on xyz date. Is that okay?
- Which date/day should I return (on)?

Similarly, is the following sentence grammatically correct?

- I booked my return ticket for my hometown for xyz date.

## Formally promoted staff members, technically the same as before – is this a good idea?

I’ve been part of a gaming community since its very beginning, and I’ve seen many decisions in these years. The most recent decision is quite confusing to me because it seems irrational to me.

Before the decision, the staff members were subdivided in supporters, moderators, and administrators. The sequence is obvious: supporters have the least technical power whereas administrators have the most. Moderators are in between. In the last years, the admins were mostly absence due to stress and other stuff and mainly managed the technical site of the community: keep the servers and the forum running, take care of urgent technical matters, etc. In game, however, moderators took the lead and took care of most matters: problems between users, small technical problems, organizing small events, etc.

You can say that moderators were the people where your problem went to first, and if it couldn’t be solved, it would be redirected to the admins (which basically happened in one of ten requests). The most recent discussion changed the system crucially: the rank moderator has been removed and all moderators have been promoted to administrators.

It actually seems like a good decision because the now promoted moderators are in game and help out even more so the workload on the “real” administrators become less. However, after some time, users suspected that the promoted moderators have been just promoted on a formal level, not on a technical level since some technical request just couldn’t be solved by the promoted ones.

Today, the staff announced that it is true. The promoted moderators have the same technical level as before, just their formal level has been increased. Their argument for their decision is that most *new users* request an admin for basically every inconvenience and just skip the moderators. On the other side, the project is relatively large (8000 monthly active users, 7000 are regular users, project is steadily growing) and it takes some time that the information is spread.

Right now, the users of the project are confused, some even demand to return to the old system. They complain that it’s not clear anymore who can do what, and they don’t know anymore who is best suited for their problem. I understand the complaint of these users. Who do you turn to if everyone is basically the same, but actually is not?

(Currently, there are 28 team members: 15 are supporters, 13 are admins, and 2 of them are the “real” ones.)

I’m quite confused. **Is it a good idea to make it look like everyone can handle your problem, although there are technical differences between the staff members who seem to be the same?**

## Question: “Unwritten” rules of baseball…If they’re not in the books or something that’s formally enforced why take them seriously or follow them?

Question: “Unwritten” rules of baseball…If they’re not in the books or something that’s formally enforced why take them seriously or follow them?