What happens if the control group differs from the treatment group?
B. Describe how analyzing the data from the treatment group sprayed with water only will increase the validity of the experimental results. C. Based on the scientist’s claim, predict which treatment group will have the smallest amount of accessible nutrients …
Why do you need a control group in an experiment?
Apr 24, 2020 · (b) Describe how analyzing the data from the treatment group sprayed with water only will increase the validity of the experimental results. (c) Based on the scientist's claim, predict which treatment group will have the smallest amount of accessible nutrients in the soil at the end of the experiment.
Who should collect and analyze data in an evaluation?
Interpreting the Confidence Interval. Meaning of a confidence interval. A CI can be regarded as the range of values consistent with the data in a study. Suppose a study conducted locally yields an RR of 4.0 for the association between intravenous drug use …
What do we mean by analyzing data?
Statistics or other analysis showed clear positive effects at a high level of significance for the people in your program and – if you used a multiple-group design – none, or far fewer, of the same effects for a similar control group and/or for a group that received a different intervention with the same purpose.
What happens if your 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 treatment in research?
The treatment is any independent variable manipulated by the experimenters, and its exact form depends on the type of research being performed. In a medical trial, it might be a new drug or therapy. In public policy studies, it could be a new social policy that some receive and not others.
How to reduce confounding variables?
There are several methods you can use to decrease the impact of confounding variables on your research: restriction, matching, statistical control and randomization. In restriction, you restrict your sample by only including certain subjects that have the same values of potential confounding variables.
How to test the effectiveness of a pill?
To test its effectiveness, you run an experiment with a treatment and two control groups. The treatment group gets the new pill. 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 ...
What does it mean to use a control group?
Then they compare the results of these groups. Using a control group means that any change in the dependent variable can be attributed to the independent variable.
What is the treatment group?
The treatment group (also called the experimental group) receives the treatment whose effect the researcher is interested in. The control group receives either no treatment, a standard treatment whose effect is already known, or a placebo (a fake treatment). The treatment is any independent variable manipulated by the experimenters, ...
What is a control group in science?
Revised on April 19, 2021. In a scientific study, a control group is used to establish a cause-and-effect relationship by isolating the effect of an independent variable. Researchers change the independent variable in the treatment group ...
How do scientists test fungi?
To test this hypothesis, the scientist divides an area within the ecosystem into multiple small plots of similar size.Equal numbers of plots are then randomly assigned to one of three treatment groups.
How do you determine if fungi are keystone species?
A scientist claims that fungi are keystone species in a particular terrestrial ecosystem. To test this hypothesis, the scientist divides an area within the ecosystem into multiple small plots of similar size.Equal numbers of plots are then randomly assigned to one of three treatment groups. Plots in the first group are sprayed with a water-soluble substance that selectively kills fungi. Plots in the second group are sprayed with a water-soluble substance that selectively kills bacteria. Plots in the third group are sprayed with the same volume of water only. After a certain period of time, the scientist then measures the amount of accessible nutrients in the soil in cach plot. (a) Describe ONE common role of both bacteria and fungi in the movement of energy and matter in ecosystems. (b) Describe how analyzing the data from the treatment group sprayed with water only will increase the validity of the experimental results. (c) Based on the scientist's claim, predict which treatment group will have the smallest amount of accessible nutrients in the soil at the end of the experiment. Justify your prediction in terms of the relative impact of a keystone species in the environment.
What is collecting data?
Essentially, collecting data means putting your design for collecting information into operation. You’ve decided how you’re going to get information – whether by direct observation, interviews, surveys, experiments and testing, or other methods – and now you and/or other observers have to implement your plan.
What are the challenges of translating qualitative data into quantitative data?
Even if most people agree on what 1 (lowest) or 5 (highest) means in regard to rating “satisfaction” with a program, ratings of 2, 3, and 4 may be very different for different people.
What are the variables that can be used to indicate changes in a dependent variable?
Various kinds of quantitative analysis can indicate changes in a dependent variable related to – frequency, duration, timing (when particular things happen), intensity, level , etc. They can allow you to compare those changes to one another, to changes in another variable, or to changes in another population.
What is qualitative information?
Unlike numbers or “hard data,” qualitative information tends to be “soft,” meaning it can’t always be reduced to something definite. That is in some ways a weakness, but it’s also a strength. A number may tell you how well a student did on a test; the look on her face after seeing her grade, however, may tell you even more about the effect of that result on her. That look can’t be translated to a number, nor can a teacher’s knowledge of that student’s history, progress, and experience, all of which go into the teacher’s interpretation of that look. And that interpretation may be far more valuable in helping that student succeed than knowing her grade or numerical score on the test.
What is qualitative data?
Qualitative data are collected as descriptions, anecdotes, opinions, quotes, interpretations, etc. , and are generally either not able to be reduced to numbers, or are considered more valuable or informative if left as narratives.
How is qualitative data changed?
Qualitative data can sometimes be changed into numbers, usually by counting the number of times specific things occur in the course of observations or interviews, or by assigning numbers or ratings to dimensions (e.g., importance, satisfaction, ease of use).
What is dependent variable?
A dependent variable is what may change as a result of the independent variable or intervention. A dependent variable could be a behavior, outcome, or other condition. A smoking cessation program, for example, is an independent variable that may change group members’ smoking behavior, the primary dependent variable.
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...
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.
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…