Unit 4 - Sampling

Question 1

Population

Answer 1

A statistical study of the entire group of individuals we want information about

Question 2

Census

Answer 2

Collects data from every individual in the population

Question 3

Sample

Answer 3

A set of individuals in the population from which we collect data

Question 4

Sample Survey

Answer 4

A study that collects data from a sample to learn about the population from which sample was selected

Question 5

Convenience sampling

Answer 5

Selects individuals from the population that are easy to reach

Question 6

Bias

Answer 6

The tendency of a sample statistic to systematically over- or under-estimate a population parameter. (This can occur through biased wording in survey questions, and conveince samples.)

Question 7

Volunteer response sampling

Answer 7

Allows people to choose to be in the sample by responding to a general invitation. (Bad! leads to bias; not representative of the entire population. Those who volunteer may have something in common) When volunteers are involved in a study, you can only make inferences about folks that are similar to those in the study.

Question 8

Random

Answer 8

Involves using a chance to process to determine are included in the sample.

Question 9

Sampling without replacement

Answer 9

An individual from a population can be selected only once.

Question 10

Sampling with replacement

Answer 10

An individual from a population can be selected more than once.

Question 11

Simple Random Sample (SRS)

Answer 11

Of size N is chosen in such a way that every group of N individuals in the population has an equal chance to be selected.

Question 12

Strata

Answer 12

Groups of individuals in a population who share characteristics thought to be associated with the variables being measured.

Question 13

Sampling

Answer 13

The process of selecting a subset, or sample, of individuals from a larger population to gather information about.

Question 14

Cluster

Answer 14

A group of individuals within a population that share a common characteristic, often geographic location, and are considered a unit for sampling purposes.

Question 15

Cluster Sampling

Answer 15

Divide the population into groups of people that mirror the population. Randomly selects select a certain number of clusters and include everyone within the clusters selected.
Pro: Convenient to carry out.

Question 16

Systematic Random Sampling

Answer 16

Selects a sample from an ordered arrangement of the population by randomly selecting one of the first individuals and choosing every nth individual thereafter.

Question 17

Undercoverage

Answer 17

Occurs when some members of the population are less likely to be chosen or cannot be chosen in a sample.

Question 18

Nonresponse

Answer 18

Occurs when an individual chosen for the sample can’t be connected or refuses to participate.

Question 19

Response Bias

Answer 19

Occurs when a systemic pattern of inaccurate answers to a survey question due to biases in the way the prompt was worded.

Question 20

Observational Study

Answer 20

Observes individuals and measures variables of interest but does not attempt to influence the responses

Question 21

Response variable

Answer 21

Measures an outcome of a study

Question 22

Explanatory variable

Answer 22

May help explain or predict changes in response variable

Question 23

Experiment

Answer 23

An experiment deliberately imposes treatments (conditions) on individuals to measure their responses

Question 24

Placebo

Answer 24

A treatment that has no active ingredient, but is otherwise like other treatment

Question 25

Treatment

Answer 25

A specific condition applied to the individuals in any experiment

Question 26

Experimental Units

Answer 26

The object/subject to which a treatment is assigned to.

Question 27

Subjects

Answer 27

When the experiment units are human beings

Question 28

Factor levels

Answer 28

In an experiment, a factor is an explanatory variable that is manipulated and may cause a change in the response variable. The different are called levels.

Question 29

Control Group

Answer 29

Used to provide a baseline for comparing the effects of other treatments.

Question 30

Placebo Effect

Answer 30

Describes the fact that some subject in an experiment will respond favorably to any treatment even an inactive treatment.

Question 31

Double-blind

Answer 31

Neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is receiving

Question 32

Single-blind

Answer 32

Either subjects or the people who interact with them and measure the response variable don’t know which treatment a subject is receiving

Question 33

Random Assignment

Answer 33

A random assignment means that the experimental units are assigned to treatments using a chance process

Question 34

Control

Answer 34

Means keeping other variables constant for all experimental wins.

Question 35

Replication

Answer 35

Giving enough treatment to enough experiment units

Question 36

Confounding

Answer 36

Occurs when two variables are associated in such way that their effects on a response variable cannot be distinguished from each other

Question 37

Completely Randomized Design

Answer 37

The experimental units are assigned to the treatments completely at random

Question 38

Block

Answer 38

A group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments.

Question 39

Randomized block design

Answer 39

An experimental design where subjects or experimental units are grouped into blocks, with the different treatments to be tested randomly assigned to the units in each block.

Question 40

Matched pair design

Answer 40

A common experimental design for comparing two treatments that use block for size 2.

Question 41

Retroprespective

Answer 41

Examine existing data for a sample of individuals

Question 42

Prospective

Answer 42

Observational studies that track individuals into the future

Question 43

Sampling variability

Answer 43

The fact that different random samples of the same size from the same population produce different estimates

Question 44

Statistically significant

Answer 44

Observed results of a study are too unusual to be explained by chance

Question 45

Random selection

Answer 45

When randomly selected the Individuals allow inference and generalization about the population from which the individuals were chosen.

Question 46

Random assignment

Answer 46

Individuals to groups allows inference about cause and effect