what are controls & variables????
got a prac coming up and need 2 know!!!
thnx xx
An independent variable is the potential stimulus or cause, usually directly manipulated by the experimenter, so it could also be called a manipulative variable.
A dependent variable is the response or measure of results.
Extraneous variables — other than the independent variable — potentially can affect the dependent variable, so they must be controlled. If possible, you try to keep them constant between the experimental and control group.
The experimental group receives the independent variable.
The control group is similar to experimental, except it does not receive the independent variable. Extraneous variables are balanced between experimental and control groups.
Types of experiments
1. Single blind gives the control group a placebo — a substance that is inert, it has no physical effect. Subjects don't know if they are in experimental or control group to reduce placebo effect, a change in behavior solely due to believing that you are getting the independent variable.
2. Double blind keeps both subjects and experimenter ignorant of group setup. Distribution of the independent variable and placebo are controlled by third party. This controls for experimenter bias and self-fulfilling prophecy, which means that experimenters with particular expectations are likely to consciously or unconsciously to bias the experiment and influence it to conform to their expectations.
As an example, suppose you want to find out if fluorides reduce dental cavities. You would find two groups, trying to control the extraneous variables. Extraneous variables are found by surveying previous research in the area. In this case, you would match the groups in terms of previous history of cavities, diet and dental hygiene habits including how and how often they brush their teeth.
The experimental group would get toothpaste with the independent variable, the fluoride, while the control group would not have the fluoride in their toothpaste. The toothpaste without the fluoride would be the placebo.
The dependent variable would be the number of cavities after participating in the experiment for a time. The dependent variable indicates the results, but it is not the results. At the end of the experiment, both groups could have no change in cavities or one of the groups could have a greater reduction in cavities. (Of course, if the fluoride increased cavities, you wouldn't want to use it.) All of these varied results would be indicated in terms of the dependent variable.
If only the subjects do not know who is getting the fluoride, it is a single blind experiment. If both the subjects and experimenter do not know, it is a double blind.
thnx...so wat would the controls & variables b for a experiment involving seperating salt from water???
What is your hypothesis? That would determine your independent and dependent variables and what you need to control..
thnx
Controls and variables are terms commonly used in scientific experiments. They play a crucial role in ensuring that the experiment is conducted accurately and that the results are reliable and meaningful.
Controls are the aspects of the experiment that are kept constant or unchanged throughout the entire experiment. They provide a baseline for comparison and help to isolate the effect of the independent variable on the dependent variable. In other words, controls help to ensure that any changes observed in the dependent variable can be attributed solely to the independent variable and not to other factors.
Variables, on the other hand, are the aspects of the experiment that are intentionally manipulated or measured. There are two main types of variables in an experiment:
1. Independent Variable: This is the variable that the researcher deliberately changes or manipulates in order to observe its effect on the dependent variable. It is sometimes referred to as the "cause" variable.
2. Dependent Variable: This is the variable that is being observed or measured in response to changes in the independent variable. It is sometimes referred to as the "effect" variable.
To understand the concept of controls and variables more clearly, let's consider an example:
Suppose you want to investigate how different amounts of fertilizer affect the growth of plants. In this experiment, the independent variable would be the amount of fertilizer, which you could vary by using different concentrations. The dependent variable would be the growth of the plants, which you would measure by recording the height or the number of leaves, for example.
To ensure accurate results, you would need to establish appropriate controls. In this case, you might use a control group of plants that receive no fertilizer at all, so that you can compare their growth to the plants receiving different amounts of fertilizer. By keeping all other factors constant, such as the amount of sunlight, temperature, and water, you can isolate the effects of the fertilizer on plant growth.
In summary, controls and variables are fundamental concepts in scientific experiments. Controls provide a baseline for comparison, while variables are manipulated or measured to observe their effect. Understanding and properly implementing controls and variables are essential for conducting reliable experiments and drawing valid conclusions.