Dental Hygiene: Which Toothbrush? In an experiment reported by J. Singer and D. Andrade in the article “Regression Models for the Analysis of Pretest/Posttest Data” (Biometrics, Vol. 53, pp. 729–735), the effect of using either a conventional or experimental (hugger) toothbrush was investigated. Twelve female and 12 male preschoolers were selected. Within each gender group, six were randomly assigned to the conventional toothbrush and the remaining six to the experimental toothbrush. After each subject brushed with the assigned toothbrush, a dental plaque index was measured. The higher the dental plaque index, the greater was the amount of plaque on an individual’s teeth. a. Is the statistical design described here a completely randomized design or a randomized block design? Explain your answer.b. If the statistical design is a randomized block design, what are the blocks?
Correlation
Correlation defines a relationship between two independent variables. It tells the degree to which variables move in relation to each other. When two sets of data are related to each other, there is a correlation between them.
Linear Correlation
A correlation is used to determine the relationships between numerical and categorical variables. In other words, it is an indicator of how things are connected to one another. The correlation analysis is the study of how variables are related.
Regression Analysis
Regression analysis is a statistical method in which it estimates the relationship between a dependent variable and one or more independent variable. In simple terms dependent variable is called as outcome variable and independent variable is called as predictors. Regression analysis is one of the methods to find the trends in data. The independent variable used in Regression analysis is named Predictor variable. It offers data of an associated dependent variable regarding a particular outcome.
Dental Hygiene: Which Toothbrush? In an experiment reported by J. Singer and D. Andrade in the article “Regression Models for the Analysis of Pretest/Posttest Data” (Biometrics, Vol. 53, pp. 729–735), the effect of using either a conventional or experimental (hugger) toothbrush was investigated. Twelve female and 12 male preschoolers were selected. Within each gender group, six were randomly assigned to the conventional toothbrush and the remaining six to the experimental toothbrush. After each subject brushed with the assigned toothbrush, a dental plaque index was measured. The higher the dental plaque index, the greater was the amount of plaque on an individual’s teeth.
a. Is the statistical design described here a completely randomized design or a randomized block design? Explain your answer.
b. If the statistical design is a randomized block design, what are the blocks?
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