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Why do you have to recode a categorical variable into dummy variables?
To capture and express differences between group means produced by categorical predictors (independent variables) using correlational/regression techniques, one typically encodes categorical variables vis-a-vis dummy, contrast or effects coding to produce vectors, each of which define a group difference in the form of a slope coefficient. Each vector can be thought of as a predictor variable which targets a single degree of freedom difference (or the difference between two group means). The correlation between a vector and the criterion (dependent variable), when squared, expresses the difference between two group means as a proportion of variance accounted for (the proportion of variance in DV accounted for by being either in grp1 or grp2). Coding allows one to easily partition the between groups variance. The vectors are always single degree of freedom values (two coded values for two groups). How many vectors? The number is equal to the degrees of freedom of the between groups term or one less than the number of groups. Take a look at Kepple & Zeddeck 1989 "data analysis for research designs". Hope this helps.
What are dummies variables?
A dummy variable is a variable that takes on the values 1 and 0; 1 means something is true. These are used in statistical analyses.
In an experiment is the control group used to test the effect of the independent variable?
i dont know u tell me you dummy
Dummy variable as an independent variable?
An independent variable is the variable you have control over, what you can choose and manipulate. It is usually what you think will affect the dependent variable. In some cases, you may not be able to manipulate the independent variable. It may be something that is already there and is fixed, something you would like to evaluate with respect to how it affects something else, the dependent variable like color, kind, time. Example: You are interested in how stress affects heart rate in humans. Your independent variable would be the stress and the dependent variable would be the heart rate. You can directly manipulate stress levels in your human subjects and measure how those stress levels change heart rate.
What is the smallest number that can be subtracted from 723 so the difference is 200 when both numbers are rounded to the nearest hundred?
700
