Continuous Random Variable (1)
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Continuous Random Variable (1)
Section 3.1-3.3
Continuous Random Variable
What is the probability that X is equal to x?
CDF for a Discrete Random Variables
Question: Is there a CDF for a continuous random variable if a PMF can not beidentified for a continuous random variable?
CDF for a Wheel-Spinning Experiment
P[X=≤ x]=x if 0 ≤X ≤1
CDF for Continuous Random Variable
• Even though it is not possible to define a PDF for a continuous random variable, it is possible to define a CDF for a random variable
PMF to CDF for a Discrete Random Variable
Theorem 2.2
Theorem 2.3
What contributes to the jump in the CDF?
Discrete RV
Continuous RV
Compare CDF of a Continuous RV to that of a Discrete RV
Discrete RV:1. Zero slope2. Jumps in CDF
Continuous RV:A continuous function
Slope of CDF function
The slope at any point x indicates the probability that X is near x.
(Just as the jump in the CDF of a discrete RV suggests non-zero probability at X=x, so does a slope in CDF of a continuous random variable?)
Probability Density Function (PDF)
It is not possible to define a PMF function for a continuous variable because P[X=x]=0.We can, however, define a probability density function.
Properties of fX(x)
PDF of X
Expected Value
Discrete Random Variable