A pharmaceutical company has developed an experimental drug...

A pharmaceutical company has developed an experimental drug meant to relieve symptoms associated with the common cold. The company identifies 300 adult males 25 to 29 years old who have a common cold and randomly divides them into two groups. Group 1 is given the experimental drug, while group 2 is given a placebo. After 1 week of treatment, the proportions of each group that still have cold symptoms are compared. (a) What is the response variable in this experiment? (b) Think of some of the factors in the study. Which are controlled? Which factor is manipulated? (c) What are the treatments? How many treatments are there? (d) How are the factors that are not controlled or manipulated dealt with? (e) What type of experimental design is this? (f) Identify the subjects. (g) Draw a diagram similar to Figure 6 or 7 to illustrate the design.

A pharmaceutical company has developed an experimental drug meant to relieve symptoms associated with the common cold. The company identifies 300 adult males 25 to 29 years old who have a common cold and randomly divides them into two groups. Group 1 is given the experimental drug, while group 2 is given a placebo. After 1 week of treatment, the proportions of each group that still have cold symptoms are compared.
(a) What is the response variable in this experiment?
(b) Think of some of the factors in the study. Which are controlled? Which factor is manipulated?
(c) What are the treatments? How many treatments are there?
(d) How are the factors that are not controlled or manipulated dealt with?
(e) What type of experimental design is this?
(f) Identify the subjects.
(g) Draw a diagram similar to Figure 6 or 7 to illustrate the design.

Key Concepts

Handling of Extraneous Variables

Extraneous variables are factors that might affect the response variable but are not the focus of the study. These are addressed by using techniques such as randomization, replication, or matching, thereby minimizing their impact and ensuring that the observed effects can be more confidently attributed to the manipulated variable.

Subjects

Subjects are the participants or entities on which the experiment is conducted. In experimental research, careful selection and definition of the study population are important to ensure that the results are reliable and can be generalized to the appropriate population.

Experimental Design

Experimental design is the overall structure of the experiment that dictates how subjects are allocated to treatments, how variables are controlled and manipulated, and how measurements are taken. A well-designed experiment, such as a randomized controlled trial, is essential for drawing valid conclusions about cause and effect.

Random Assignment

Random assignment is a process used to allocate subjects to different experimental groups in a way that minimizes selection bias. It ensures that each subject has an equal chance of being assigned to any group, which helps balance both known and unknown confounding factors across treatment groups.

Response Variable

The response variable is the outcome measured in an experiment, used to assess the effect of different treatments. It reflects the effect of the independent variable on a measurable attribute, such as the presence or absence of symptoms in subjects after treatment.

Manipulated Variable

The manipulated variable, also known as the independent variable, is the factor that the researcher actively changes or assigns in order to observe its effect on the response variable. In an experiment, this is typically the treatment given to each group, distinguishing one group from another.

Controlled Factors

Controlled factors are variables that are held constant across the experimental groups to reduce confounding effects. By controlling these aspects, such as subject age, gender, or health status, researchers ensure that any differences observed in the response variable are more likely attributable to the treatments applied.

Treatments

Treatments refer to the different conditions or interventions administered to subjects in an experiment. They represent the specific variations in the manipulated variable, such as receiving an experimental drug versus a placebo, and are critical for comparing the effects on the response variable.

Transcript

00:01 In this particular problem, we are looking at a pharmaceutical company who has a new experimental drug, and they're going to assign two groups out of 150 adult males with a common cold and see which of the two groups work.

00:17 Actually, in this case, the experimental drug versus a placebo.

00:22 So part a, we are looking at the response variable, and that is how did they recover? so how do they recover from their cold symptoms based off of the two drugs? part b, what are some factors in the study? age could have an impact, which that is control because you only took a certain age group.

00:52 Different drug treatment.

00:54 That is the one that is manipulated because they are randomly assigning those two things.

01:00 That's what gives you the experimental design.

01:03 Also, other health factors, do they smoke or not? and those are sort of controlled by the randomization, which we'll talk about actually in part d.

01:14 If we want to go ahead and skip down there, how are the factors that are not controlled? how do you account of experimental design is by randomizing things, we can account for things like health factors.

01:27 Do they smoke or not? do they have prior issues? maybe they have allergies.

01:32 Then there is the randomization is what helps you to do away with that group c or number part c is what are your two treatments the experimental drug there's treatment one and the placebo is treatment two as you can see this is an completely randomized design because each individual is not receiving both and comparing them in fact it is a completely randomized design by the way it's set up part f what are the those are the 300 adult males that are in that age group, 25 to 29.

02:12 So a pretty small age group there with a common cold.

02:19 So they all do have a common cold...

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