Essential

Question 1

5 Sampling Methods

Answer 1

1. Simple Random Sampling
2. Stratified Sampling
   Sample from the groupeds
3. Cluster Sampling
   Sample the groupeds
4. Systematic Sampling
   k≈N/n (round down)
   N: Population ct.
   n: Sample ct.
5. Convenience Sampling

Question 2

When constructing
Freq. Distribution

How to determine
Number of Classes
& Class Width

Answer 2

Useful guide:
2ᵏ > n
→ k > ㏑n/㏑2
(Round UP)

Width = (Max - Min) / k

Question 3

Chebyshev’s Theorem:
Non-Normal Proportion Data Set
How to find k in
μ ± kσ or
xbar ± ks

Answer 3

% ≥ 1- 1/k²

Question 4

Chebyshev’s Theorem:
Empirical Rule

when:
μ ± 1σ
μ ± 2σ
μ ± 3σ

Answer 4

≈68%
≈95%
≈99.7%

(μ@middle)

Question 5

In Discrete Probability Distribution

Mean
&
Variance

Answer 5

Mean μ = E(x)
= ∑ [ P(x)·x ]

Variance σ²
= ∑ [ P(x)·(x-μ)² ]

Question 6

In Binomial Probability Formula

Mean μ
&
Variance σ²

Answer 6

Mean
μ = n·p

Variance
σ² = n·p·q

Question 7

In Poisson Probability Distribution

Mean μ = E(x)
&
Variance σ²

Answer 7

Mean
λ = μ = E(x)
= n·p

Variance
λ = σ²
= n·p·q

Question 8

P(A | B) =

Answer 8

Given B has occurred

P(A & B)
P(A | B) =—————
P(B)