MATH 225N STATISTICS WEEK 6 FINAL EXAM 25 QUESTION

MATH 225N STATISTICS WEEK 6 FINAL EXAM 25
QUESTIONS WITH 100% CORRECT ANSWERS/ ACTUAL
EXAM
Population - ANSWER: The whole set of items that are of interest

Census - ANSWER: Observes or measures every member of a population

Sample - ANSWER: A selection of observations taken from a subset of the population
which is used to find out information about the population as a whole

Census - Adv & Disadv - ANSWER: Adv
- Completely accurate

Disadv
- Time consuming & expensive
- Cannot be used when the testing process destroys the item
- Hard to process large quantity of data

Sample - Adv & Disadv - ANSWER: Adv
- Less time consuming & less expensive than a census
- Fewer people have to respond
- Less data to process than in a census

Disadv
- Data may not be as accurate
- May not be large enough to reflect about subsets in population

Sampling units - ANSWER: Individual units of a population

Sampling frame - ANSWER: Sampling units of a population individually named or
numbered to form a list

Simple random sampling - ANSWER: Number the list from 001 to ______
Select x random numbers using random number generator
Ignore repeats
Continue until you have x numbers
Select corresponding items from the data sheet

Systematic sampling - ANSWER: The required elements are chosen at regular
intervals from an ordered list

Stratified sampling - ANSWER: The population is divided into mutually exclusive
strata and a random sample is taken from each
- proportion of each strata sampled should be the same

, Stratified sampling formula - ANSWER: The number sampled in a stratum = (number
in stratum / number in population) x overall sample size

Simple random sampling - Adv & Disadv - ANSWER: Adv
- Free of bias
- Easy & cheap to implement for small populations and small samples
- Each sampling unit has a known and equal chance of selection

Disadv
- Not suitable when the population size or the sample size is large
- A sampling frame is needed

Systematic sampling - Adv & Disadv - ANSWER: Adv
- Simple and quick to use
- Suitable for large samples and large populations

Disadv
- A sampling frame is needed
- It can introduce bias if the sampling frame is not random

Stratified sampling - Adv & Disadv - ANSWER: Adv
- Sample accurately reflects the population structure
- Guarantees proportional representation of groups within a population

Disadv
- Population must be clearly classified into distinct strata
- Not suitable when the population size or the sample size is large
- A sampling frame is needed

Quota sampling - ANSWER: How many members of each group you wish to sample is
decided in advance and opportunity sampling is used until you have a large enough
sample for each group

Opportunity sampling - ANSWER: Consists of taking the sample from people who are
available at the time the study is carried out and who fit the criteria you are looking
for

Quantitative variable - ANSWER: Data associated with numerical observations

Qualitative variable - ANSWER: Data associated with non-numerical observations

Mode / Modal class - ANSWER: -Qualitative and quantitative data
-The value or class that occurs most often
-Not informative if each value occurs once

Median (Q2) - ANSWER: -((n+1)/2)th term
-The middle value when the data values are put in order