Posted: 4/12/2013 6:19:03 AM EDT
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So my wife's daughter and her husband are expecting their 5th. They just found out its girl #5.
Assuming 50/50 boy / girl odds per child, how do you factor in each new child's odds of being a girl? What are these odds of a 5 girl run, assuming all other things are equal or normal. |
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Quoted: The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. But the probability of getting ALL 5 is pretty low, 3.125% as already noted. Odds are by now, there is something in the biological process that is making having a girl more likely, which may change the odds of having a boy to something far less than 50%. |
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Quoted: The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. This. Everytime you flip the coin, it's a 50/50 chance. just because it landed on heads 50 times in a row, does not mean the chances go up that tails will land next.
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The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. This. Everytime you flip the coin, it's a 50/50 chance. just because it landed on heads 50 times in a row, does not mean the chances go up that tails will land next. The probability of getting ten heads in a row is (1/2)^10, but that's not Bayes theorem. ETA: previous poster is talking about the total probably, not the probability of each occurance. I read it incorrectly the first run through. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. yeah, it's not 50/50 when you are failing to account for the ingredients being lopsided. Daddy controls the sex, and some men are more disposed to producing male or female coded sperm. So, you would have to run some sample stats on numbers of female producing sperm vs. male producing sperm of that individual male in order to have an accurate representation of the odds of male vs female for that individual. In other words, the coin is lopsided.....more like a 30/70 coin for example, rather than a 50/50 coin (as in it would have a 30% chance for male, 70% for female), and THEN run your statistics |
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Quoted: I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me.
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me. but your coin is assumed to be fair. the man's sperm may not be exactly 50/50 ratio of chance. in order for the coin test to be valid, the coin has to be a fair coin........ |
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Quoted: Quoted: Quoted: I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me. but your coin is assumed to be fair. the man's sperm may not be exactly 50/50 ratio of chance. why do you assume it's the guys fault? blame it on whose fault it really is, the woman  well, it's at least a 50/50 chance it's the woman...or are you gonna tell me it's 30/70 |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me. but your coin is assumed to be fair. the man's sperm may not be exactly 50/50 ratio of chance. why do you assume it's the guys fault? blame it on whose fault it really is, the woman well, it's at least a 50/50 chance it's the woman...or are you gonna tell me it's 30/70 Failed high school biology? |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me. but your coin is assumed to be fair. the man's sperm may not be exactly 50/50 ratio of chance. why do you assume it's the guys fault? blame it on whose fault it really is, the woman well, it's at least a 50/50 chance it's the woman...or are you gonna tell me it's 30/70 Failed high school biology? While it is yahoo answers, here's a pretty good explanation of what I am trying to tell you. http://answers.yahoo.com/question/index?qid=20090108193139AAvnkCK here's a better source http://www.nature.com/scitable/topicpage/the-sex-of-offspring-is-determined-by-6524953 so who failed HS bio again? If the man's sperm is more X dominant, he will produce more girls........xx chromosome. if the man's sperm is more y dominated, he will produce more males do a punnet square, and get back to me. Remember, a sperm is 1/2 a genetic code, not the full thing. So you only get 1 x or 1 y chromosome, not xx or xy on a single sperm. the female always provides an x, so therefore........ since the male can provide either an x or a y, HE DOES DETERMINE THE SEX OF THE CHILD. now eat your crow. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. yeah, it's not 50/50 when you are failing to account for the ingredients being lopsided. Daddy controls the sex, and some men are more disposed to producing male or female coded sperm. So, you would have to run some sample stats on numbers of female producing sperm vs. male producing sperm of that individual male in order to have an accurate representation of the odds of male vs female for that individual. In other words, the coin is lopsided.....more like a 30/70 coin for example, rather than a 50/50 coin (as in it would have a 30% chance for male, 70% for female), and THEN run your statistics We are obviously assuming a fair coin here. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. yeah, it's not 50/50 when you are failing to account for the ingredients being lopsided. Daddy controls the sex, and some men are more disposed to producing male or female coded sperm. So, you would have to run some sample stats on numbers of female producing sperm vs. male producing sperm of that individual male in order to have an accurate representation of the odds of male vs female for that individual. In other words, the coin is lopsided.....more like a 30/70 coin for example, rather than a 50/50 coin (as in it would have a 30% chance for male, 70% for female), and THEN run your statistics We are obviously assuming a fair coin here. see my post above for why the fair coin test is invalid for this situation. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. yeah, it's not 50/50 when you are failing to account for the ingredients being lopsided. Daddy controls the sex, and some men are more disposed to producing male or female coded sperm. So, you would have to run some sample stats on numbers of female producing sperm vs. male producing sperm of that individual male in order to have an accurate representation of the odds of male vs female for that individual. In other words, the coin is lopsided.....more like a 30/70 coin for example, rather than a 50/50 coin (as in it would have a 30% chance for male, 70% for female), and THEN run your statistics We are obviously assuming a fair coin here. see my post above for why the fair coin test is invalid for this situation. it doesn't change the way we determine the total probability, it only changes the numbers used. Let's say your right and it's a 70/30 coin, 70% for a boy and 30 for a girl. although there's no evidence to suggest that. for each iteration, the chances of having a girl is 3/10 and a boy 7/10. chances of having 10 boys in a row is (7/10)^10 chances of having 10 girls in a row is (3/10)^10 ETA: i really doubt that the bias in the coin would be THAT drastic. i could buy 5.2/10 but not 7/10. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. yeah, it's not 50/50 when you are failing to account for the ingredients being lopsided. Daddy controls the sex, and some men are more disposed to producing male or female coded sperm. So, you would have to run some sample stats on numbers of female producing sperm vs. male producing sperm of that individual male in order to have an accurate representation of the odds of male vs female for that individual. In other words, the coin is lopsided.....more like a 30/70 coin for example, rather than a 50/50 coin (as in it would have a 30% chance for male, 70% for female), and THEN run your statistics We are obviously assuming a fair coin here. see my post above for why the fair coin test is invalid for this situation. it doesn't change the way we determine the total probability, it only changes the numbers used. Let's say your right and it's a 70/30 coin, 70% for a boy and 30 for a girl. although there's no evidence to suggest that. for each iteration, the chances of having a girl is 3/10 and a boy 7/10. chances of having 10 boys in a row is (7/10)^10 chances of having 10 girls in a row is (3/10)^10 ETA: i really doubt that the bias in the coin would be THAT drastic. i could buy 5.2/10 but not 7/10. What I am saying, is P(girl I boy) is dependent on the individual sperms genetic contents, is it not? Therefore, is it not probable that a man could be more predisposed to producing x sperm, than y sperm? That is what I am trying to say here. P(girl I boy) is different for every person, hell, every sexual encounter......until you have tested his sperm let's say > 30 ejaculations, you can't have an accurate assumption about the ratio of x containing sperm to y containing sperm. The 70/30 was an EXAMPLE to illustrate a point, not a number I calculated from anything.........just a hypothetical, think about this........kind of thing. |
| It impossible to use a simple formula to calculate the probability. You have so many variables, such as were the dudes balls exposed to cold water for long periods? Was he a fighter, or did he suffer a lot of blows to the sack? All of these variables affect the composition of his sperm. |
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The odds are currently 50/50 given that the other births have already happened. Simple Bayesian probability. A five girl run is .5^5=.03125 or 3.125% This is correct... We just covered this subject in medical school 2 weeks ago... As some have posted, the probability is 1/2 each time, but because now we have further information (such as that they have had 5 girls in arrow), that information is inputed as a Bayesian calculation... The more one phenotype is expressed, the more chance there is it will be repeated... It has been established that there is a predisposition for females in the family, so the possibility of a boy is 3.125% versus 96.875% for a girl the next time around. |
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The odds are currently 50/50 given that the other births have already happened. Simple Bayesian probability. A five girl run is .5^5=.03125 or 3.125% This is correct... We just covered this subject in medical school 2 weeks ago... As some have posted, the probability is 1/2 each time, but because now we have further information (such as that they have had 5 girls in arrow), that information is inputed as a Bayesian calculation... The more one phenotype is expressed, the more chance there is it will be repeated... It has been established that there is a predisposition for females in the family, so the possibility of a boy is 3.125% versus 96.875% for a girl the next time around. :) thank you so very much. I'd kiss you if you weren't a guy. |
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Quoted: Quoted: The odds are currently 50/50 given that the other births have already happened. Simple Bayesian probability. A five girl run is .5^5=.03125 or 3.125% This is correct... We just covered this subject in medical school 2 weeks ago... As some have posted, the probability is 1/2 each time, but because now we have further information (such as that they have had 5 girls in arrow), that information is inputed as a Bayesian calculation... The more one phenotype is expressed, the more chance there is it will be repeated... It has been established that there is a predisposition for females in the family, so the possibility of a boy is 3.125% versus 96.875% for a girl the next time around. Bullshit. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. Yeah, the biology side of it screws with the probability. It's not equally likely that an "X" chromosome sperm will fertilize the egg vs. a "Y" chromosome sperm. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. yeah, it's not 50/50 when you are failing to account for the ingredients being lopsided. Daddy controls the sex, and some men are more disposed to producing male or female coded sperm. So, you would have to run some sample stats on numbers of female producing sperm vs. male producing sperm of that individual male in order to have an accurate representation of the odds of male vs female for that individual. In other words, the coin is lopsided.....more like a 30/70 coin for example, rather than a 50/50 coin (as in it would have a 30% chance for male, 70% for female), and THEN run your statistics We are obviously assuming a fair coin here. see my post above for why the fair coin test is invalid for this situation. it doesn't change the way we determine the total probability, it only changes the numbers used. Let's say your right and it's a 70/30 coin, 70% for a boy and 30 for a girl. although there's no evidence to suggest that. for each iteration, the chances of having a girl is 3/10 and a boy 7/10. chances of having 10 boys in a row is (7/10)^10 chances of having 10 girls in a row is (3/10)^10 ETA: i really doubt that the bias in the coin would be THAT drastic. i could buy 5.2/10 but not 7/10. What I am saying, is P(girl I boy) is dependent on the individual sperms genetic contents, is it not? Therefore, is it not probable that a man could be more predisposed to producing x sperm, than y sperm? That is what I am trying to say here. P(girl I boy) is different for every person, hell, every sexual encounter......until you have tested his sperm let's say > 30 ejaculations, you can't have an accurate assumption about the ratio of x containing sperm to y containing sperm. The 70/30 was an EXAMPLE to illustrate a point, not a number I calculated from anything.........just a hypothetical, think about this........kind of thing. Yeah i think you're getting a little carried away. No one is trying to nail it down to that level of detail. |
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The odds are currently 50/50 given that the other births have already happened. Simple Bayesian probability. A five girl run is .5^5=.03125 or 3.125% This is correct... We just covered this subject in medical school 2 weeks ago... As some have posted, the probability is 1/2 each time, but because now we have further information (such as that they have had 5 girls in arrow), that information is inputed as a Bayesian calculation... The more one phenotype is expressed, the more chance there is it will be repeated... It has been established that there is a predisposition for females in the family, so the possibility of a boy is 3.125% versus 96.875% for a girl the next time around. :) thank you so very much. I'd kiss you if you weren't a guy. it's total probability, information of the priors has no effect on the future results. it's just total probability. if I roll a 4 on a dice, the next time I roll i am not more or less likely to not roll a 4 because I just rolled one. |
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The assumption is that there are not any medical or physical factors influencing the outcomes.
It is possible that a medical condition is skewing the probability strongly in favor of female children. Without information we don't have, the odds cannot be truly calculated. We can make a biased guess based on assuming 50-50 odds. Quoted:
The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. |
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Quoted:
The assumption is that there are not any medical or physical factors influencing the outcomes. It is possible that a medical condition is skewing the probability strongly in favor of female children. Without information we don't have, the odds cannot be truly calculated. We can make a biased guess based on assuming 50-50 odds. Quoted:
The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. right we all understand that, and no one is claiming to specify anything beyond the assumptions. ETA: since the US population is roughly 49.2 male 50.8% female a fair coin assumption is close enough for GD probability estimation. ETA2: even if there was a little bias, say instead of 5/10 it was 5.1/10, the new TOTAL probability would be (5.1/10)^5 = 3.3831% which is not much different than 3.125% ETA3: now if you want to get really stupid with it, the above M/F ratio is from the US census and is the ratio for ALL ages. BUT since F's tend to live longer than M's it is actually skewed in favor of Fs. If we take say the M/F ratio of the US population under 5 yrs old the skew shifts the other way. 51.1%M 48.9%F. So for the whole population of the US under age 5 there are more boys than girls. |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me. but your coin is assumed to be fair. the man's sperm may not be exactly 50/50 ratio of chance. why do you assume it's the guys fault? blame it on whose fault it really is, the woman well, it's at least a 50/50 chance it's the woman...or are you gonna tell me it's 30/70 Biology not your strong suit, I take it? |
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I don't think biology is the same as a coin. Five in a row would indicate a tendency for the dad to make girlies. There is not even remotely close to enough evidence to suggest this. The sample size is way to small. His next 5 kids could all be males, would you sing the same tune then? or would you be dissecting the probability of having 5 females and then 5 males in a row? go start flipping a coin, the patterns are amazing if you've never recorded them before. go do 1000 flips, record them, then get back to me. but your coin is assumed to be fair. the man's sperm may not be exactly 50/50 ratio of chance. why do you assume it's the guys fault? blame it on whose fault it really is, the woman well, it's at least a 50/50 chance it's the woman...or are you gonna tell me it's 30/70 Failed high school biology? While it is yahoo answers, here's a pretty good explanation of what I am trying to tell you. http://answers.yahoo.com/question/index?qid=20090108193139AAvnkCK here's a better source http://www.nature.com/scitable/topicpage/the-sex-of-offspring-is-determined-by-6524953 so who failed HS bio again? If the man's sperm is more X dominant, he will produce more girls........xx chromosome. if the man's sperm is more y dominated, he will produce more males do a punnet square, and get back to me. Remember, a sperm is 1/2 a genetic code, not the full thing. So you only get 1 x or 1 y chromosome, not xx or xy on a single sperm. the female always provides an x, so therefore........ since the male can provide either an x or a y, HE DOES DETERMINE THE SEX OF THE CHILD. now eat your crow. Dude, he was on your side. 
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The odds are currently 50/50 given that the other births have already happened. Simple Bayesian probability. A five girl run is .5^5=.03125 or 3.125% This is correct... We just covered this subject in medical school 2 weeks ago... As some have posted, the probability is 1/2 each time, but because now we have further information (such as that they have had 5 girls in arrow), that information is inputed as a Bayesian calculation... The more one phenotype is expressed, the more chance there is it will be repeated... It has been established that there is a predisposition for females in the family, so the possibility of a boy is 3.125% versus 96.875% for a girl the next time around. :) thank you so very much. I'd kiss you if you weren't a guy. it's total probability, information of the priors has no effect on the future results. it's just total probability. if I roll a 4 on a dice, the next time I roll i am not more or less likely to not roll a 4 because I just rolled one. You're not allowing for the possibility that there was a REASON, other than chance that the priors were female. It MAY have an effect on future results. It's not necessarily completely chance. |
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The assumption is that there are not any medical or physical factors influencing the outcomes. It is possible that a medical condition is skewing the probability strongly in favor of female children. Without information we don't have, the odds cannot be truly calculated. We can make a biased guess based on assuming 50-50 odds. Quoted:
The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. right we all understand that, and no one is claiming to specify anything beyond the assumptions. ETA: since the US population is roughly 49.2 male 50.8% female a fair coin assumption is close enough for GD probability estimation. ETA2: even if there was a little bias, say instead of 5/10 it was 5.1/10, the new TOTAL probability would be (5.1/10)^5 = 3.3831% which is not much different than 3.125% ETA3: now if you want to get really stupid with it, the above M/F ratio is from the US census and is the ratio for ALL ages. BUT since F's tend to live longer than M's it is actually skewed in favor of Fs. If we take say the M/F ratio of the US population under 5 yrs old the skew shifts the other way. 51.1%M 48.9%F. So for the whole population of the US under age 5 there are more boys than girls. You can't use a population average to discuss one particular couple. I have a friend who had two boys, both born with an extremely rare cranial condition that until then, the medical field believed the condition to be chance. He was part of a study to prove that there was more to it. |
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Quoted: So my wife's daughter and her husband are expecting their 5th. They just found out its girl #5. Assuming 50/50 boy / girl odds per child, how do you factor in each new child's odds of being a girl? What are these odds of a 5 girl run, assuming all other things are equal or normal. its 50% for a girl (the previous births have no effect on the chance of the next birth) If you had asked that question about the chances of having 5 girls in a row, the answer would have been .5^5 |
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The assumption is that there are not any medical or physical factors influencing the outcomes. It is possible that a medical condition is skewing the probability strongly in favor of female children. Without information we don't have, the odds cannot be truly calculated. We can make a biased guess based on assuming 50-50 odds. Quoted:
The dice have no memory. Previous births have NO effect on future births. Therefore, the odds of having a girl each time are always 50%. Bayes has nothing to do with it. right we all understand that, and no one is claiming to specify anything beyond the assumptions. ETA: since the US population is roughly 49.2 male 50.8% female a fair coin assumption is close enough for GD probability estimation. ETA2: even if there was a little bias, say instead of 5/10 it was 5.1/10, the new TOTAL probability would be (5.1/10)^5 = 3.3831% which is not much different than 3.125% ETA3: now if you want to get really stupid with it, the above M/F ratio is from the US census and is the ratio for ALL ages. BUT since F's tend to live longer than M's it is actually skewed in favor of Fs. If we take say the M/F ratio of the US population under 5 yrs old the skew shifts the other way. 51.1%M 48.9%F. So for the whole population of the US under age 5 there are more boys than girls. You can't use a population average to discuss one particular couple. I have a friend who had two boys, both born with an extremely rare cranial condition that until then, the medical field believed the condition to be chance. He was part of a study to prove that there was more to it. no shit. since we don't have specific details we use assumptions. ETA: you obviously didn't read the first line, which said we are using assumptions and not attempting to estimate anything outside of those. |
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There are multiple causes for the ration being pulled off 'fir' (50-50).
Some on the women's part (mucus viscosity in the reproductive tract can give a slight advantage to Y sperm since they weigh less), to the male not producing an even 50-50 from temperature, chemical exposure, and probably many more we have not really determined. One way of increasing odds is to centrifuge the sperm (the Xs are heavier and settle closer to the bottom) and then take sperm from the top of the sample for artificial insemination. The statistics of large populations rarely apply in individual cases perfectly. If they did we would all die at the same expected age. There is a reason many things are computed as averages. |
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There are multiple causes for the ration being pulled off 'fir' (50-50). Some on the women's part (mucus viscosity in the reproductive tract can give a slight advantage to Y sperm since they weigh less), to the male not producing an even 50-50 from temperature, chemical exposure, and probably many more we have not really determined. One way of increasing odds is to centrifuge the sperm (the Xs are heavier and settle closer to the bottom) and then take sperm from the top of the sample for artificial insemination. The statistics of large populations rarely apply in individual cases perfectly. If they did we would all die at the same expected age. There is a reason many things are computed as averages. again for like the 1000th time, we are not trying to estimate the specific factors, SINCE WE DON'T KNOW WHAT THEY ARE, we can reasonably and easily estimate the that probability is around 3%. ETA: and your premise could not be more wrong, read about the law of large numbers. probability and statistics is a science used to describe and make inferences about things observed in nature. |