# Probabilty of sequential deaths

• statistically_challe
In summary, the conversation discusses the Birthday problem and the odds of blood relatives dying on a significant date, taking into account different calendars. The question is how to calculate these odds and the U.S. Social Security Period Life Table is referenced. There is a debate about finding connections after the fact and the likelihood of at least one person having multiple relatives die on a significant day.
statistically_challe
Hi all,

I hope today finds you well and in good spirits.

I'm trying to develope a statistical model and haven't done so in years. Any help is appreciated.

The Birthday problem goes something like this:

The question is:-

"How many people should be gathered in a room together before it is more likely than not that two of them share the same birthday?"

The compound probability of birthday 2 being different from birthday 1, and of birthday 3 being different from the other two, these being independent outcomes, is:-

(364/365)*(363/365) = 0.991796 or 99.2% chance that two people will not share the same birthday.

My question goes something like this:

My question is what are the odds of blood relatives dying on a personally or globally significant date (See below).

We observe two calendars in the family, Gregorian (Greek Orthodox) for religious purposes, and Julian (standard).

Helene, Jean, and Xenia are my aunts. Estelle and Edward are my mother and father.

****Name*****Birth *******Death**Age*Date Sign.*Calendar
1999 Helene--01 Oct 1911--09 Jan 1999-88-Christmas---Gregorian

2000 Jean*---07 Sep 1913--26 Dec 2000-87-Christmas--Julian

2001 Estelle--31 May 1925--28 Dec 2001-76-Christmas--Julian

2002 None

2003 None

2004 None

2005 Xenia----31 Dec 1917--11 Sep 2005-88-9/11--------Julian

2006 Edward--15 May 1921--07 Sep 2006-85-Sister Jean--Julian
---------------------------------------------Birthday*

At this point I have the U.S. Social Security Period Life Table.
http://www.ssa.gov/OACT/STATS/table4c6.html

Discounting for illness, which most of us die from, I'd like to derive the "odds".

Even pieces of the model would be helpful. Any help is appreciated.

Statictically Challenged

The problem is that it's easy to find connections after the fact. Assuming a 365-day year with a fixed calendar, the chance that any three given people would die on Christmas is 1/365^3. The chance that exactly three out of five given people would die on Christmas on one of two calendars is roughly 80/365^3. The chance that at least three out of five given people would die on a 'significant day' in one of two calendars is higher yet. The chance that, out of the six billion plus people in the world, at least one would have three or more relatives die on a 'significant day' in one of two calendars is essentially 100%.

,

First of all, it's great to see someone trying to develop a statistical model and seeking help to do so. It's always a good idea to brush up on skills and ask for assistance when needed.

Now, onto your question about the probability of blood relatives dying on significant dates. This is a challenging question to answer definitively, as there are many factors that could influence the likelihood of this occurring. However, we can approach it by breaking it down into smaller parts and trying to estimate the probabilities for each part.

First, let's consider the probability of two people sharing the same birthday, as in the Birthday problem. As you mentioned, the probability of two people not sharing the same birthday is about 99.2%. However, in your case, you are interested in the probability of two people sharing a specific date, such as Christmas or 9/11. This probability would be much lower, as there are only a few significant dates in a year compared to 365 possible birthdays. Without knowing the specific dates that your family members passed away on, it's difficult to estimate this probability accurately.

Next, let's consider the probability of a blood relative dying on a significant date. This would depend on the number of blood relatives and the number of significant dates in a year. In your family, there are three blood relatives and two significant dates (Christmas and 9/11). Assuming that each person has an equal chance of passing away on either of these dates, the probability of a blood relative dying on a significant date would be about 6.7% (2/30).

However, this probability would change if we consider the ages and genders of your family members. For example, if all of your family members were female and lived to be 85 years old, the probability of one of them passing away on a significant date would be much higher than if they were a mix of ages and genders. Additionally, the fact that your family observes two different calendars could also influence the probability, as certain dates may hold more significance in one calendar compared to the other.

In terms of using the U.S. Social Security Period Life Table, this could potentially help you estimate the likelihood of your family members passing away at a certain age. However, as mentioned before, there are many factors that could influence the probability in your specific situation. It may be helpful to consult with a statistician or conduct further research to refine your model and estimate the probabilities more accurately.

1.

## What is the probability of sequential deaths?

The probability of sequential deaths refers to the likelihood of multiple deaths occurring in a specific order or sequence. This can be calculated using mathematical formulas and statistical analysis.

2.

## How is the probability of sequential deaths calculated?

The probability of sequential deaths is calculated by multiplying the individual probabilities of each death occurring in the specified sequence. For example, if the probability of death A occurring is 0.2 and the probability of death B occurring is 0.3, then the probability of sequential deaths in the order of A then B would be 0.2 x 0.3 = 0.06, or 6%.

3.

## What factors influence the probability of sequential deaths?

The probability of sequential deaths can be influenced by a variety of factors, including the individual probabilities of each death occurring, the order or sequence of the deaths, and any potential correlations between the deaths.

4.

## Can the probability of sequential deaths be used to predict future deaths?

While the probability of sequential deaths can provide insights into the likelihood of multiple deaths occurring in a specific sequence, it cannot be used to predict future deaths with absolute certainty. Other factors, such as external events and individual health conditions, may also play a role in determining the occurrence of deaths.

5.

## How does understanding the probability of sequential deaths benefit society?

Understanding the probability of sequential deaths can help inform decision-making in various fields, such as insurance and healthcare. It can also aid in risk assessment and disaster planning, as well as contribute to advancements in statistical analysis and probability theory.