Study Session 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? Randomization Control Replication

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 sample b) multi-stage cluster sample c) stratified sample d) convenience sample e) 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 help a) 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 NOT a) similar to a stratified random sample for surveys b) 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 comparisons e) 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 new medicine for migraine headaches. She decides to conduct a clinical trial on 100 randomly selected adults who get migraine headaches at a rate of one per week or more. Although age and gender are not of primary interest in the trials, the researcher is concerned that these factors may impact the effectiveness 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 new medicine for migraine headaches. She decides to conduct a clinical trial on 100 randomly selected adults who get migraine headaches at a rate of one per week or more. Although age and gender are not of primary interest in the trials, the researcher is concerned that these factors may impact the effectiveness 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 Measure number of headaches & compare Measure number of headaches & compare