Treatment FAQ

b) compute how many unique verticals in the control and in treatment groups.

by Annabel Stehr Published 2 years ago Updated 2 years ago

What happens if the control group differs from the treatment group?

If your control group differs from the treatment group in ways that you haven’t accounted for, your results may reflect the interference of confounding variables instead of your independent variable.

What is a control group in a research study?

A control group is a group separated from the rest of the experiment such that the independent variable being tested cannot influence the results. This isolates the independent variable's effects on the experiment and can help rule out alternative explanations of the experimental results.

What is the difference between Control Group 1 and 2?

Control group 1 gets an identical-looking sugar pill (a placebo) Control group 2 gets a pill already approved to treat high blood pressure Since the only variable that differs between the three groups is the type of pill, any differences in average blood pressure between the three groups can be credited to the type of pill they received.

What are the two types of control groups?

Positive and negative controls are two other types of control groups: 1 Positive control groups are control groups in which the conditions guarantee a positive result. Positive control groups... 2 Negative control groups are control groups in which conditions produce a negative outcome. Negative control groups help... More ...


What are differences caused by experimental treatment?

Differences caused by an experimental treatment can be thought of as just one part of the overall variability of measurements that originates from many sources. If we measured the strength of the response of cockroach retinas when stimulated by light, we would get a range of measurements. Some of the variability in measurements could be due to ...

What is the goal of experimental science?

We have seen previously that a major goal of experimental science is to detect differences between measurements that have resulted from different treatments. Early on we learned that it is not possible to assess these differences based on a single measurement of each treatment. Without knowing how much variation existed within a treatment, we could not know if the difference between treatments was significantly large. The simplest and first formal statistical test we learned about, the t -test of means, provided a mathematical way of comparing the size of differences of means relative to the variability in the samples used to calculate those means.

Most recent answer

Thank you Amir. I did question I did the average weight both groups . I got big variance. when I can use average weight instad normal average . what about ifs did not averse weight.

Popular Answers (1)

The t-test and ANOVA require independence among observations. Since your design includes time, it creates temporal correlations. So, these two options are too much simple. The Repeated Measures ANOVA has an assumption called "Sphericity", which is rarely met. I suggest you an alternative approach.

All Answers (10)

This seems to be a 2 x 3, between x within (repeated measures design); correct me if I'm wrong. If it indeed is a between x within design, just run a two-way ANOVA: group x time. In Excel you would have 6 rows corresponding to 2 groups (control vs.

What is the difference between an experimental group and a control group?

These two groups should be identical in every respect except one: the difference between a control group and an experimental group is that the independent variable is changed for the experimental group, but is held constant in the control group.

What is controlled experiment?

A simple example of a controlled experiment may be used to determine whether or not plants need to be watered to live. The control group would be plants that are not watered. The experimental group would consist of plants that receive water. A clever scientist would wonder whether too much watering might kill the plants and would set up several experimental groups, each receiving a different amount of water.

What is an experimental group?

An experimental group is a test sample or the group that receives an experimental procedure. This group is exposed to changes in the independent variable being tested. The values of the independent variable and the impact on the dependent variable are recorded. An experiment may include multiple experimental groups at one time.

What is the independent variable?

The independent variable is "controlled" or held constant in the control group. A single experiment may include multiple experimental groups, which may all be compared against the control group. The purpose of having a control is to rule out other factors which may influence the results of an experiment. Not all experiments include ...

What is a positive and negative control?

Positive and negative controls are two other types of control groups: Positive control groups are control groups in which the conditions guarantee a positive result. Positive control groups are effective to show the experiment is functioning as planned. Negative control groups are control groups in which conditions ...

Is a placebo a control group?

A placebo may also be used in an experiment. A placebo isn't a substitute for a control group because subjects exposed to a placebo may experience effects from the belief they are being tested.

Do all experiments have an experimental group?

While all experiments have an experimental group, not all experiments require a control group.


Control Groups in Experiments

  • Control groups are essential to experimental design. When researchers are interested in the impact of a new treatment, they randomly divide their study participants into at least two groups: 1. The treatment group (also called the experimental group) receives the treatment whose effect the researcher is interested in. 2. The control groupreceives e...
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Control Groups in Non-Experimental Research

  • Although control groups are more common in experimental research, they can be used in other types of research too. Researchers generally rely on non-experimental control groups in two cases: quasi-experimental or matching design.
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Importance of Control Groups

  • Control groups help ensure the internal validityof your research. You might see a difference over time in your dependent variable in your treatment group. However, without a control group, it is difficult to know whether the change has arisen from the treatment. It is possible that the change is due to some other variables. If you use a control group that is identical in every other way to t…
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