# Sajang Yang

## Thursday, July 28, 2011

### TeXLive 2011 released!

I'm happy to know that TeXLive 2011 is available ( http://www.tug.org/texcollection/ ), and I'm currently downloading the iso image from TUG( http://www.tug.org/texlive/acquire-iso.html ).

Hopefully I'll try to install TeXLive 2011 in the weekend or next week.

## Thursday, July 21, 2011

### The Two Laws of Probability (Bulmer, 1979)

If A and B are mutually exclusive events, that is if they cannot both occur together, then the probability that either A or B will occur is equal to the sum of their separate probabilities:

P(A or B) = P(A) + P(B)

In general, if A and B are any two events, not necessarily mutually exclusive, the probability that A or B will occur is the sum of their separate probabilities minus the probability that they both occur:

P(A or B) = P(A) + P(B) - P(A and B)
or

P(A) + P(B) = P(A or B) + P(A and B)

#R-code Table 2(a/b)
> Table2a = rbind(c(359881, 8609), c(340454, 7796))

> rownames(Table2a) = c("Male", "Female")
> Table2a
[,1] [,2]
Male 359881 8609
Female 340454 7796

> colnames(Table2a) = c("Liveborn", "Stillborn")
> Table2a
Liveborn Stillborn
Male 359881 8609
Female 340454 7796

> prop.Table2a = prop.table(Table2a)
> prop.Table2a
Liveborn Stillborn
Male 0.5021082 0.01201133
Female 0.4750035 0.01087703

> sum.prop.Table2a
Liveborn Stillborn Sum
Male 0.5021082 0.01201133 0.5141195
Female 0.4750035 0.01087703 0.4858805
Sum 0.9771116 0.02288836 1.0000000

>

If A and B are two events, then the probability that both A and B will occur is equal to the probability that A will occur multiplied by the conditional probability that B will occur given that A has occurred,

P(A and B) = P(A) x P(B|A)

The conditional probability of an event B givent another event A, written P(B|A), is the probability that B will occur if we consider only those occasions on which A also occurs; it is thus the limiting value of the proportion n(A and B) / n(A), where n(A and B) is the number of times on which both A and B have occurred and n(A) is the number of times on which A has occurred.P(B|A) = n(A and B) / n(A)

When the conditional probability of B given A is equal to the unconditional, or absolute, probability of B the two events are said to be "statistically independent".

If A and B are statistically independent, P(B|A) = P(B) and the law of multiplication takes the simple form

P(A and B) = P(A) x P(B)

The Law of Multiplication

### The Two Concepts of Probability (Bulmer, 1979)

Statistical probability & Inductive probability

Statistical probability
- It is an empirical concept.
- We can never know with certainty the exact probability of an event.

Inductive probability
- logical concept.

## Monday, July 18, 2011

### To My Baby-Daughter

Quote from Rocky Balboa:

No matter what happens, you are my daughter and my blood.
You're the best thing in my life.

I love you. - Dad -