Ch. 14

Question 1

Goals of experiments?

Answer 1

• Eliminate bias
• Reduce sampling error (by increasing precision and power)

Question 2

Design features that reduce bias

Answer 2

• Controls
• Random assignment to treatments
• Blinding

Question 3

Controls

Answer 3

A group which is identical to the experimental treatment in all respects aside from the treatment itself.

Question 4

Confounding variable

Answer 4

A variable that masks or distorts casual relationship between measured variables in a study

Question 5

Experimental artifact

Answer 5

Experimental artifact is a bias in a measurement produced by unintended consequences of experimental procedures

Question 6

Clinical Trial

Answer 6

Experimental study in which two or more treatments are applied to human participants

Question 7

Methods of Reducing Bias?

Answer 7

• Simultaneous control group
• Randomization
• Blinding

Question 8

Placebo Effect

Answer 8

An improvement in a medical condition that results from the psychological effects of medical treatment

Question 9

Randomization

Answer 9

The random assignment of rtreatments to units in an experimental study

Question 10

Advantage of randomization?

Answer 10

Random assignment averages out the effects of confounding variables

Question 11

Blinding

Answer 11

Process of concealing information from participants (sometimes including researcers) about which individuals recieve which treatment

(Prevents behaviour change)

Question 12

Single-blind experiment

Answer 12

Participants unaware of treatment recieved

Question 13

Double-blind experiment

Answer 13

Like single-blind, except researchers administering the treatment and measuring the respons are unaware of which treatments the subjects are recieving

Question 14

Methods of reducing the effects of sampling error?

Answer 14

• replication
• balance
• blocking

basically minimizing the “noise”

Question 15

Replication

Answer 15

The application of every treatment to multiple, independent experimental units

Question 16

How does replication reduce sampling error?

Answer 16

More units = more info = better estimates = more power

Question 17

Balanced Experimental design

Answer 17

A experimental design in which all treatments have the same sample size

Question 18

Blocking

Answer 18

The grouping of experimental units that have similar properties. Within each block, treatments are randomly assined experimental units

Question 19

Randomized Block design

Answer 19

Like paired design, but for more than 2 treatmentsx

Question 20

How does blocking work?

Answer 20

Group experimental units together, so that extraneous various between groups are accounted for

(ex. testing the treatment of a drug, but grouping patients by clinic because of potential extraneous variation between clinics)

Question 21

Extreme treatments

Answer 21

Make treatments stronger to force an increase in the signal-to-noise ratio.

Help make detecting a response easier

Question 22

Factor

Answer 22

A factor is a single treatment variable whose effects are of interest to the researcher

Question 23

Factorial design

Answer 23

An experimental design in which all treatment combinations of two or more variables are investigated. A factorial design can measure interactiosn between treatment varialbes (ex. no effect w/ increased water or increased oxygen alone, but increasing both simultaneously have an effect)

Question 24

Interaction

Answer 24

An interaction between two (or more) explanatory variables means that the effect of one variable depends on the state of the other variable.

Question 25

Matching

Answer 25

A strategy in which every individual in the treament group is paired with a control individual having the same or closely similar values for the suspected confounding variables.

(cannot account for all confounds)