Unit 3: Sampling and Experimentation

Question 1

Population

Answer 1

The entire group we want information about

Question 2

Sample

Answer 2

A part of the population that we use to gather information about the entire population

Question 3

Census

Answer 3

Collects data from every individual in the population

Question 4

Observational Study

Answer 4

observes individuals and measures variables of interest but doesn’t influence the responses

Question 5

Experiment

Answer 5

purposefully imposes treatment on individuals to observe their responses

Question 6

What kind of study is a sample survey?

Answer 6

Observational Study

Question 7

Convenience Sampling

Answer 7

Definition: Using subjects that are readily available

Advantages: Easy and less expensive to collect

Disadvantages: Not representative of the population
(e.g.) standing outside the library and asking the first 10 students if they like school

Question 8

Voluntary Response Sample

Answer 8

Obtained by allowing subjects to decide whether or not to respond

Advantages: easy to collect
Disadvantages: People who choose to respond probably have really strong opinions

Question 9

Simple Random Sample

Answer 9

Individuals chosen from a population in such a way that each person has an equal chance of getting selected as everyone else

Advantages: Easy to accomplish by using a random number generator

Disadvantages: None

Question 10

Stratified Random Sample

Answer 10

Divide population into groups of similar individuals (strata) and then take a simple random sample of each individual group

Advantages: May produce more exact information

Disadvantages: No appropriate if the strata you are using aren’t clearly defined.

Question 11

Systematic Random Sampling

Answer 11

randomly select a starting point and then choose every nth person

Advantages: Every member has an equal probability of being selected
Disadvantages: Not every sample size of n has an equal chance of being selected

Question 12

Without Replacement

Answer 12

When an item selected from a population can only be chosen onece

Question 13

With Replacement

Answer 13

When an Item from a population can be chosen more than once.

Question 14

Biased

Answer 14

systematically not representative of the entire population

Question 15

Voluntary Response Bias

Answer 15

just using volunteers will probably not be representative of the entire population

Question 16

Undercoverage

Answer 16

Certain groups within the population are left out of the process of choosing a sample

Question 17

Non response

Answer 17

occurs when an individual for a sample can’t be contacted or won’t respond

Question 18

Response Bias

Answer 18

biased caused by the behavior of the respondent or the interviewer

Question 19

Untruthful Answers

Answer 19

People giving untruthful answers to sensitive questions, social norms, and interviewer bias

Question 20

Ignorance

Answer 20

people will say dumb things when responding to questions they don’t know the answer to to make themselves look better.

Question 21

Lack of Memory

Answer 21

People may not remember the answers to a question

Question 22

Timing

Answer 22

The time that the survey is taken may have an impact on the answer.

Question 23

Phrasing

Answer 23

Differences in a way a question is phrased could influence the answers

Question 24

Sampling error

Answer 24

difference between the sampling result and the result of the entire population. error results from chance variation. It can be minimized by increasing the sample size

Question 25

Non-Sampling Error

Answer 25

Occurs when sampling data are incorrectly, collected, recorded, or analyzed

Question 26

Benefits of Experiements

Answer 26

• we are able to study the information that we want while controlling other variables

-allow us to study the combined effects of several factors

Question 27

Factors

Answer 27

Explanatory variable in the experiment

Question 28

Level

Answer 28

various groups that factors take

Question 29

What are the four critical elements of experimental design

Answer 29

• Comparison
• Randomization
• Control
• Replication

Question 30

Comparison

Answer 30

Make sure that groups you are comparing don’t differ greatly. prevent this using randomization

Question 31

Randomization

Answer 31

Most important element of the experiment. Can do it in either the process of selection or process of distributing treatments

Question 32

Control

Answer 32

Treated like the baseline for the experiment. Experimental Units in the control group will be in the same conditions as the other groups, however they will not receive treatment

Question 33

Replication

Answer 33

Using enough experimental units so that effects caused by the treatment can be distinguished from effects caused by the sampling error.

Question 34

Blinding

Answer 34

when the subject doesn’t know whether or not they are receiving the placebo

Question 35

Double Blinding

Answer 35

When the subject nor experimenter know whether or not they are receiving the placebo

Question 36

Completely Randomized Design

Answer 36

experimental units are assigned to treatment completely by chance.

-Treatment + Control groups will be completely equal in size

Question 37

Lurking

Answer 37

When there’s an outside variable that controls each of the two variables and makes it appear as if they have a correlation

Question 38

Confounding

Answer 38

When there is another is explanatory variable that you did not control that may be affecting the outcome, but you wouldn’t know.

Question 39

Matched Pair Design

Answer 39

designs in which the same individual or two matched individuals are assigned both a control and a placebo. Should be conducted as double blind. If an individual takes part, the order in which they get the placebo and the real treatment should be random

Question 40

Block Designs

Answer 40

Randomized design is taken on multiple broken down groups of the experimental units

Question 41

What does random selection of individuals do? (inference)

Answer 41

Allows us to make inferences about the population

Question 42

What does random assignment of treatments do? (inference)

Answer 42

Allows us to make inference about the cause and effect of two variables