Week+16+Variables

There are several models of scientific investigation. Crudely, we can think of: a. The experimenterer manipulates the conditions in one variable, and is testing the effect of this maniupation on one or more variables. (e.g. Studying the effect of sleeping hours on student success in school). b. The experimenterer is collecting and listing data without the manipulation of conditions. For example, this would fit the study of fossils, or the search for new, undocumented species in the wild.

To simplify our research proposal project we will only use examples that belong to the first category.

 **1)** **Variables** : When conducting experiments one must be aware of which she is maniupating ("**Independent Variable**") and which one she will measure as a result ("**Dependent Variables**"). In the first type of study, these variables are often mentioned in the research question, or even in the title of the publication about the study.

One trick I learned in helping students identify the dep. and indep. variables is to imagine putting them on a graph. The variable that you imagine being on the __y-axis__, would be __the dependent variable__, and the variable on the __x-axis__, would be the __independet variable__. (F//or example, in the effect of sleep on student success, the dependent variable would be students' test scores, or grades, and the independent variable - the average hours of sleep).//

In order to make sense of the results, only one independent must be manipulated at a time. This demands that any other variables that are not being tested, will remain constant. These are called **Constant Variables** or **controlled variables.**

When the experimenterer decides which variables to maintain constant, he is neutralizing effects that might confuse the interpretation of the results. //For example, when testing the effect of sleeping hours on student success, one needs to make sure that the participants slept in the same bed each time, and that they were tested in the same subjects in school. Otheriwse, we won't be able to tell if it is the sleeping hours that affected student success, or where the student is sleeping, or the subject he was tested on.//

**2) Controls:**
====These would be conditions in the experiment to which we are comparing the results of our manipulation. Usually a control condition is more "normal", or it is the untreated parts of the experiment. ==== In the assignment this week, you will need to identify the variables in the study of boosting the breast milk action against HIV.

//For example, in the sleep effect study, the control would be "normal" sleep time for the participant. // =‍Breast Milk Antibody Fights HIV but Needs Boost, Study **Finds** = []