Thread: Creating a probability density function for a discrete random variable

1. Creating a probability density function for a discrete random variable

Okay, so the issue is I'm given this variable, with the distribution

p(x_1) = .2
p(x_2) = .3
p(x_3) = .3
p(x_4) = .2

How would I go about making a density function for this variable? x_1,x_2,x_3,x_4 are constants. Thanks!

2. Originally Posted by bryan05s
Okay, so the issue is I'm given this variable, with the distribution

p(x_1) = .2
p(x_2) = .3
p(x_3) = .3
p(x_4) = .2

How would I go about making a density function for this variable? x_1,x_2,x_3,x_4 are constants. Thanks!
Post the actual question, exactly as it's worded.

3. Oh I'm sorry, I meant like a density function.. the problem is I'm trying to compute a Likelihood ratio for a null and alternative hypothesis, so obviously to create the ratio I need to divide the two likelihood functions. Thus in order to do this I need to have the density function for this distribution (and if I know how to make this density function I can make the one for the alternative hypothesis, of course )

Actual question is

Let x have one of the following distributions:..

(The one i posted earlier, H_0, and H_A is.. x_1 = .1 x_2 = .4 x_3 = .1 x_4 = .4)

Compute the likelihood ratio, for each possible value X and order the x_i according to the likelihood ratio. (Need help on this second part too, I'm sure it's easy, I just don't understand what this question is asking me)

4. Please, I need to know how to solve this soon. Sorry for the rush