Continuous Random Variable (1)

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Continuous Random Variable (1) Section 3.1-3.3

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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 be identified for a continuous random variable?. - PowerPoint PPT Presentation

Transcript of Continuous Random Variable (1)

Page 1: Continuous Random Variable (1)

Continuous Random Variable (1)

Section 3.1-3.3

Page 2: Continuous Random Variable (1)

Continuous Random Variable

What is the probability that X is equal to x?

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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?

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CDF for a Wheel-Spinning Experiment

P[X=≤ x]=x if 0 ≤X ≤1

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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

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PMF to CDF for a Discrete Random Variable

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Theorem 2.2

Theorem 2.3

What contributes to the jump in the CDF?

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Discrete RV

Continuous RV

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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

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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?)

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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.

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Properties of fX(x)

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PDF of X

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Expected Value

Discrete Random Variable