Study Session

Experimental Design

Experimental Design

1. Which of the following is true regarding the difference between an observational study and and an experiment?a) An experiment must have a control group whereas the observational study does not.b) An observational study is used for human subjects whereas an experiment is used for non-human subjects.c) In an experiment, the investigator randomly places

subjects into treatment and control groups whereas in an observational study, the subjects are placed into groups based on a characteristic.d) The observational study can produce causal results

whereas an experiment can only identify an association.e) None of these is true.

Experimental Design

Which of the following is true regarding the difference between an observational study and and an experiment?

c) In an experiment, the investigator randomly places subjects into treatment and control groups whereas in an observational study, the subjects are placed into groups based on a characteristic.

Experimental Design

What are the three principles of experimental design?

Experimental Design

What are the three principles of experimental design?

RandomizationControlReplication

Experimental Design

3. In an experiment, if two variable are confounded, which of the following statements is true?

a) One of the variables must be a lurking variable.

b) There is a clear indication that a placebo effect is present in the experiment.

c) The investigator cannot separate the effect of the variables on a response variable.

d) None of these is true.

Experimental Design

In an experiment, if two variable are confounded, which of the following statements is true?

c) The investigator cannot separate the effect of the variables on a response variable.

Experimental Design

Which one of the following statements about experiments is true?a) All experiments must have a control group.b) Blocking is employed to reduce variation.c) Random assignment is only critical for treatment groups, as opposed to control groups.d) Matching can be used in any experiment to eliminate lurking variables.e) None of these is true.

Experimental Design

Which one of the following statements about experiments is true?

b) Blocking is employed to reduce variation.

Experimental Design

A randomized block design is similar to which of the following sampling designs?

a) simple random sampleb) multi-stage cluster samplec) stratified sampled) convenience samplee) systematic sample 

Experimental Design

A randomized block design is similar to which

of the following sampling designs?

c) stratified sample 

Experimental Design

Blocking is utilized to helpa) organize the treatment and control groups b) counteract the placebo effect.c) produce groups that are as similar as

possible.d) avoid the need for randomization.e) replicate the experiment within each

block

Experimental Design

Blocking is utilized to help

c) produce groups that are as similar as possible.

Experimental Design

A randomized block design is NOTa) similar to a stratified random sample for surveysb) a strategy to control for an influence that would

affect the outcome of the experiment.,c) a strategy that depends on randomization.d) only used for gender comparisonse) All of these describe a randomized block design.

Experimental Design

A randomized block design is NOT

d) only used for gender comparisons

Experimental Design

A medical researcher is interested in testing a newmedicine for migraine headaches. She decides toconduct a clinical trial on 100 randomly selectedadults who get migraine headaches at a rate of oneper week or more. Although age and gender are notof primary interest in the trials, the researcher isconcerned that these factors may impact theeffectiveness of the drug. Describe how she should set up her experiment for the 100 subjects without considerations of age and gender. A graphic is an acceptable answer.

Experimental Design

 Describe how she should set up her experiment for the 100 subjects without considerations of age and gender. A graphic is an acceptable answer.

Randomize

50 adults new drug

50 adults old drug

Measure and compare number of headaches

Experimental Design

A medical researcher is interested in testing a newmedicine for migraine headaches. She decides toconduct a clinical trial on 100 randomly selectedadults who get migraine headaches at a rate of oneper week or more. Although age and gender are notof primary interest in the trials, the researcher isconcerned that these factors may impact theeffectiveness of the drug. Describe how she should set up her experiment for the 100 subjects if she wishes to control for gender. 

Experimental Design

Describe how she should set up her experiment for

the 100 subjects if she wishes to control for gender.

-It is believed that males and females will respond differently to the drug, so we block by gender.

Male

Female

New drug

Old drug

New drug

New drug

Measure number of headaches & compare

Measure number of headaches & compare

Barron’s Problems

P. 369 #12, 18, 25, 33, 34

P. 377 #3

P. 430 #1