Ch 5-6 Midterm

Question 1

Simple random sample

Answer 1

Process that selects sample of “n” objects so each member of population has same probability of being selected

Question 2

Why we achieve greater accuracy by obtaining random sample

Answer 2

1. Difficult to measure every item
2. Proper selected samples can be used to obtain estimates of population characteristics
3. By using probability distribution we can determine error with estimates

Question 3

Sampling distribution

Answer 3

Probability distribution of sample mean

Question 4

Sample distribution of sample mean

Answer 4

Population mean

Question 5

When variance of Sample mean decreases…

Answer 5

Sample size “n” increases

Question 6

When do we use standard normal distribution for sample mean?

Answer 6

When sample mean is normal distribution

Question 7

Central limit theorem

Answer 7

Distribution of sample approximated a normal distribution (bell curve) as sample size increaes

Question 8

Law of large numbers

Answer 8

Sample mean will approach population mean as sample size “n” becomes large regardless of distribution

Question 9

Acceptance intervals

Answer 9

Intervals within which sample mean has high probability of occurring given we know variance and mean

Question 10

Probability of range using CDF

Answer 10

P(a < x < b) = F(b) - F(a)

Question 11

Properties of density function

Answer 11

1. Area under pdf f(x) = 1.0
2. f(x) > 0 for all values x
3. Probability X lies between a and b under pdf

Question 12

Expected value

Answer 12

Average of values taken as numbers of N

Question 13

What does mean provide

Answer 13

Measure of centre of Distribution

Question 14

What does variance provide

Answer 14

Measure of dispersion

Question 15

Linear functions of random variable

Answer 15

W = a + bX