1.4 Experimental Design

Question 1

What are three key elements of a well-designed experiment?

Answer 1

control, randomization & replication

Question 2

confounding factor

Answer 2

occurs when an experimenter cannot determine the difference between the different factors effecting the variable, making it hard to tell what is truly causing the observed outcome.

Question 3

placebo effect

Answer 3

subject reacts favorably to a placebo but was given a fake treatment

Question 4

blinding

Answer 4

subjects do not know whether they are receiving a treatment or a placebo

Question 5

double-blind experiment

Answer 5

neither the experimenter no the subjects know whether the subjects are receiving the treatment or placebo

Question 6

randomization

Answer 6

process of randomly assigning subjects to different treatment groups

Question 7

completely randomized design

Answer 7

subjects are randomly assigned to different groups

Question 8

what are blocks?

Answer 8

groups of subjects with similar characteristics

Question 9

randomized block designs

Answer 9

Subjects grouped into blocks based on a characteristic (age, gender, etc), then within the blocks are randomly assigned to different treatment groups

Question 10

matched-pairs design

Answer 10

Two subjects with similar characteristics matched together

one assigned as the treatment group & the other = control group

Question 11

replication

Answer 11

repetition of an experiment under the same or similar conditions

Question 12

census

Answer 12

count or measure of an entire population

Question 13

sampling

Answer 13

count or measure of a part of the population and is more commonly used in statistical studies

Question 14

what is one technique to guard against a sampling error?

Answer 14

Use a random sample

Question 15

what is a stratified sample?

Answer 15

A “sample” of each strata of the population

Question 16

what is a cluster sample?

Answer 16

divide the population into groups called clusters

select all of the members in one or more (but not all) of the clusters

care must be taken to ensure that the members of clusters have similar characteristics

Question 17

systematic sample

Answer 17

Every person in a population is assigned a # and then at regular intervals a person is chosen for the study

Question 18

what is a convenience sample?

Answer 18

common use is randomly stopping people in shopping malls to ask them questions

Question 19

What is important to remember in a stratified sample?

Answer 19

Strata used must be in proportion to actual % of occurrences in population

Question 20

What to remember about systematic samples?

Answer 20

Regular patterns in data will skew results