An empirical distribution turns a finite sample into a probability distribution by assigning every observation weight 1/n. For five coin tosses yielding H, H, T, T, T, heads has probability 2/5 and tails 3/5. Its expectation equals the sample average, while the unobserved data-generating distribution describes the process that produced the sample. section 1.5.1
Use the empirical distribution to:
- Represent an observed dataset as a probability distribution when the data-generating distribution is unavailable. section 4.2.1
- Apply the adjustment formula by weighting each observed row equally, giving every configuration probability 1/n. section 4.2.1
- Handle continuous variables without requiring integrals in practice, because the empirical distribution has at most n observed outcome values. section 4.2.3
Five coin tosses
Encode heads as 1 and tails as 0. The sample (1, 1, 0, 0, 0) assigns probability 1/5 to each toss, producing an empirical probability of 2/5 for heads and a sample average of 2/5. section 1.5.1
Table 4.4 Empirical distribution in a case with multiple confounders
|
Y
|
X
|
Z
1
|
…
|
Z
p
|
Empirical probability
|
|---|---|---|---|---|---|
|
y
1
|
x
1
|
z
1
1
|
…
|
z
1
p
|
1/
n
|
|
y
2
|
x
2
|
z
2
1
|
…
|
z
2
p
|
…
|
|
y
3
|
x
3
|
z
3
1
|
…
|
z
3
p
|
1/
n
|
Inspect how equal 1/n weights represent rows containing outcomes, treatments, and multiple confounders. section 4.2.1
