# If theres a 15% probability each month of getting a woman pregnant...

How many times do I need to have sex each month to ensure it will happen one of those months?

Does it statistically have to happen sooner or later? Say I live for 250 years and copulate absurd amount of times.

Shouldn't a statistician be better equipped to answer this than a biologist?

Where did 15% chance per month come from? Especially without listing the assumptions, it makes no sense.

BillTre and russ_watters
Does it statistically have to happen sooner or later?
For a random distribution, never is possible but vanishingly unlikely.

Suppose you have a box with 17 white balls and 3 red ball. If you pick one at random (and put it back) many times you are likely to get a red one 15% of the time. But it may be that you never do. This is fundamental to the concept of randomness.

Whether real world things are actually random is an different question.

https://ecampusontario.pressbooks.pub/introstats/chapter/3-7-joint-probabilities/#:~:text=A repeated trial experiment can,event on the second trial.

Shouldn't a statistician be better equipped to answer this than a biologist?

This is a question only answerable by SCOTUS. Let's add it to the docket: I bet they will grant cert.

BillTre
In other words, no, there is no guarantee you will get someone pregnant, no matter how many times you try.

By the way, it is not just a game of chance. Various biological factors may mean you may not be able to conceive together at all. Consult with your doctor.

BillTre
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC188498/ said:
Conception is most likely to occur in the first month of trying (about a 30% conception rate). The chance then falls steadily to about 5% by the end of the first year. Cumulative conception rates are around 75% after six months, 90% after a year, and 95% at two years.
For the probability of conception based on WHEN the intercourse happens - as opposed to HOW OFTEN - you can see this study: https://www.demographic-research.org/volumes/vol3/5/3-5.pdf

berkeman said:
Where did 15% chance per month come from? Especially without listing the assumptions, it makes no sense.
.
At age 30, a woman has a 20% chance conception each month. Up to 85% of women at this age will be pregnant within the first year of attempting conception. At age 35, there is a 15% chance per month of conception. At age 40, the chance of conception is 5% per month.

"Conception is most likely to occur in the first month of trying (about a 30% conception rate)"

Why??

DaveC426913 said:
In other words, no, there is no guarantee you will get someone pregnant, no matter how many times you try.

By the way, it is not just a game of chance. Various biological factors may mean you may not be able to conceive together at all. Consult with your doctor.
But a probability distribution should distribute all outcomes given enough tries.

That's what distribution means

DaveE said:
For a random distribution, never is possible but vanishingly unlikely.

Suppose you have a box with 17 white balls and 3 red ball. If you pick one at random (and put it back) many times you are likely to get a red one 15% of the time. But it may be that you never do. This is fundamental to the concept of randomness.

Whether real world things are actually random is an different question.

https://ecampusontario.pressbooks.pub/introstats/chapter/3-7-joint-probabilities/#:~:text=A repeated trial experiment can,event on the second trial.
Randomness is irrelevant. If the cosmos is deterministic, it can still be impossible since it' not part of the chain of events

.
At age 30, a woman has a 20% chance conception each month. Up to 85% of women at this age will be pregnant within the first year of attempting conception. At age 35, there is a 15% chance per month of conception. At age 40, the chance of conception is 5% per month.

It looks like those numbers are for women who are trying to conceive, so most likely they are having sex pretty often during those months. So your question below is irrelevant, no?

How many times do I need to have sex each month to ensure it will happen one of those months?

berkeman said:
It looks like those numbers are for women who are trying to conceive, so most likely they are having sex pretty often during those months. So your question below is irrelevant, no?
I didn't think of that, actually. You outsmarted a genius (according to my professors.)

berkeman
How about this then. If there's true randomness in the universe, and she remains 35 at infinity. will I get a baby out of her eventually?

Airplane probability is expressed like this:

"In fact, based on this incredible safety record, if you did fly every day of your life, probability indicates that it would take you nineteen thousand years before you would succumb to a fatal accident."

https://anxieties.com/self-help-resources/fear-of-flying/how-safe-is-flying/

Randomness is irrelevant. If the cosmos is deterministic, it can still be impossible since it' not part of the chain of events
It's kind of a weird way of looking at this.

Are the spermatozoa in good condition?
Are the ova in good condition?
Does the sperm fit in with parameters of the female? Viscosity, acidity, alkalinity?
Will the sperm like the molecular make up of the environment?
If fertilization happens is the uterus a good environment?

Tick those boxes then sex when she is ovulating provides a good chance.
Given those conditions are positive, I would guess 15% seems low for two healthy compatible individuals.

Individuals are quite different though, not something you can find out on the first date.
Him "Do you have a hostile uterus?"
Her "What?"
Him "Sorry I said is that hostel new to us?"
Her "What?"
Him "You have the look of Liv Tyler."

Last edited:
russ_watters
The probability is probably a collection of various male sperms into an average.
pinball1970 said:
It's kind of a weird way of looking at this.

Are the sperms in good condition?
Are the ova in good condition?
Does the sperm fit in with parameters of the female? Viscosity, acidity, alkalinity?
Will the sperm like the molecular make up of the environment?
If fertilization happens is the uterus a good environment?

Tick those boxes then sex when she is ovulating provides a good chance.
Given those conditions are positive, I would guess 15% seems low for two healthy compatible individuals.

Individuals are quite different though, not something you can find out on the first date.
Him "Do you have a hostile uterus?"
Her "What?"
Him "Sorry I said is that hostel new to us?"
Her "What?"
Him "You have the look of Liv Tyler you know."
A

The probability is probably a collection of various male sperms into an average.

A
So just based on sperm?

pinball1970 said:
So just based on sperm?
Various women, various males into an average and then probability. You obviously don't base it on one persons fertility level. The average woman age 35 will try to get pregnant with a male around her age. So that's why it's as high 15.

I read another data which claimed 12%

Btw, the airplane probability statement is false. It's based on induction.

It's safe by such a margin that it doesn't matter, but the math is garbage.

It is not possible to calculate airplane probability.

Put it like this: if events were stastically uniform from now on, their probability figure would be correct.

If there's true randomness in the universe, and she remains 35 at infinity.
How can anyone remain "35 at infinity"?

BillTre and pinball1970
"Conception is most likely to occur in the first month of trying (about a 30% conception rate)"

Why??
I'm not sure how to respond to that. It seems it was observed that if 100 women have sex regularly around their ovulation period, 30 of them will get pregnant. It is an observation, not an explanation.

I'm not sure why this statement seems to NOT answer your question:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC188498/ said:
Cumulative conception rates are around 75% after six months, 90% after a year, and 95% at two years.
I further give you a visual cue of the statement (from the same link):

So, out of 100 women who have intercourse each month around their ovulation period, 95 will get pregnant within 24 months. If that number may still slightly increase in time, of course, this will never reach 100 as infertility is a reality.

So to relate to this statement:
"In fact, based on this incredible safety record, if you did fly every day of your life, probability indicates that it would take you nineteen thousand years before you would succumb to a fatal accident."
"In fact, if a woman had sex regularly every month, probability indicates that it would take less than 2 years before she would get pregnant."

russ_watters
jack action said:

"In fact, if a woman had sex regularly every month, probability indicates that it would take less than 2 years before she would get pregnant."
That's assuming the probability figure doesn't change with the arrow of time. But of course it does, she gets older.

Sex is actually a great subject for probability theory. There is no real evidence that pregnacy is caused by any particular technique, so you can really dumb it down to pure numbers and average sperm count/fertility figures

You outsmarted a genius (according to my professors.)
This thread is in the Biology/Medical forum. Therefore I (rightly, IMO) assumed it was asking the question in the context of biology/medicine, which is a rather ... messy discipline.

So I request clarification: is this a biology/medicine question, or is it a stats question?

If the former, there are many factors involved in conception and pregnancy that must be considered before seeming any kind of sensical answer.

If the latter, I request that this be moved to the appropriate math forum where it will draw the kind of dialogue desired.

DaveC426913 said:
This thread is in the Biology/Medical forum. Therefore I (rightly, IMO) assumed it was asking the question in the context of biology/medicine, which is a rather ... messy discipline.

So I request clarification: is this a biology/medicine question, or is it a stats question?

If the former, there are many factors involved in conception and pregnancy that must be considered before seeming any kind of sensical answer.

If the latter, I request that this be moved to the appropriate math forum where it will draw the kind of dialogue desired.
It is a stats question

It is a stats question
Thank you. I suspected as much.

I have asked the Mods to move it to the appropriate forum so you can get the activity you seek.

It is a stats question
Can you summarize your stats question(s)? Thanks.

berkeman said:
Can you summarize your stats question(s)? Thanks.

If given millions (or trillions) of trials in one month, would a fertile agent impregnate a female counterpart by necessity, if she carries a probability amplitude of 15%?

The answer has to be yes, or I'm not the genius they make me out to be.

So my real question is, how many trials would the agent need? It's a perverted but fun question.

The airplane crash probability statement is wrong for another reason besides asymetrical time evolution (no fixed stats.)

Suppose we can save me after an airplane crash... And I go through the 19 000 flights regardless

There is no reason why my first flight doesn't crash by random distribution, and the rest 18 999 are crash free.

The only thing that can be calculated as fact (assuming the past stats are set in stone), is that I will die once in 19 000 flights. You won't know which one of the flights it is.

So they are tricking the reader, but not me...

I'm going to tie off this thread here, so you can start a new thread in the Statistics forum with your questions. Please be sure to post links to your reading there, and if you can post some math behind your assertions, that would help. Thanks.

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