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Probability Question
3 messages · Matilda E. Gogos, Peter Dalgaard, David Winsemius
On Dec 28, 2011, at 05:11 , Matilda E. Gogos wrote:
Hello, This is a question from a class I'm not in (it's also winter break). But, all the same, I don't know where to start in R with this. It's supposed to be done in R. So, can anyone direct me with a helpful hint or 2, on how to get started with the question listed below, or tell me how I can re-post this to Usenet groups sci.stat.consult., so they can help with this question:
We're not supposed to help with homework here, and neither is sci.stat.consult. However, since it is Christmas... This looks like a pen-and-paper (theory) exercise, not an R one. Are you sure that the R requirement is not intended to apply to exercises further down the list? You might use expand.grid() to find the elements of the powerset, but I'm not sure that actually helps understanding.
Exercise 1. Let ? = {H,T,E}(a set with 3 elements, called H ,T and E . You
can think of ?heads?, ?tails? and ?edge? if you like, but this
interpretation is not necessary).
1. List the elements of the powerset P (?) of ?. (Recall that the powerset
of a set is the set of all subsets of that set, including ? (the empty set)
and the whole set.)
2. Suppose P is a set function on ? (that is, a rule assigning real numbers
to subsets of ?). Suppose that
P({H,T}) = 3, P({H,E}) = 3, P({H}) = 1 444
Why is it impossible that P is a probability measure ? (That is, no matter
how P is defined on the remaining subsets of ?, it can?t be a probability
measure.)
--
Best,
Matilda Gogos
matildaelizabethv at gmail.com
[[alternative HTML version deleted]]
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com
On Dec 28, 2011, at 3:15 AM, peter dalgaard wrote:
On Dec 28, 2011, at 05:11 , Matilda E. Gogos wrote:
Hello, This is a question from a class I'm not in (it's also winter break). But, all the same, I don't know where to start in R with this. It's supposed to be done in R. So, can anyone direct me with a helpful hint or 2, on how to get started with the question listed below, or tell me how I can re- post this to Usenet groups sci.stat.consult., so they can help with this question:
We're not supposed to help with homework here, and neither is sci.stat.consult. However, since it is Christmas... This looks like a pen-and-paper (theory) exercise, not an R one. Are you sure that the R requirement is not intended to apply to exercises further down the list? You might use expand.grid() to find the elements of the powerset, but I'm not sure that actually helps understanding.
Exercise 1. Let ? = {H,T,E}(a set with 3 elements, called H ,T and
E . You
can think of ?heads?, ?tails? and ?edge? if you like,
but this
interpretation is not necessary).
1. List the elements of the powerset P (?) of ?. (Recall that the
powerset
of a set is the set of all subsets of that set, including ? (the
empty set)
and the whole set.)
I don't think I'm violating the no homework rule too much by pointing our that there is a powerset() function in the sets package. Why one wouldn't do this one in their head is a bit beyond me, but if it's really true that these need to be done in R, then maybe the author's intent ti to get that package installed and loaded?
2. Suppose P is a set function on ? (that is, a rule assigning real
numbers
to subsets of ?). Suppose that
P({H,T}) = 3, P({H,E}) = 3, P({H}) = 1 444
Why is it impossible that P is a probability measure ? (That is, no
matter
how P is defined on the remaining subsets of ?, it can?t be a
probability
measure.)
--
Best,
Matilda Gogos
matildaelizabethv at gmail.com
David Winsemius, MD West Hartford, CT