Category: Statistics
Changing Reference Level in Dummy Coding in R
You can change the reference level in dummy coding in R by using the following R code. contr.treatment(total_levels, base = Number_reference_level) Step 1: Prepare Data The following R code generates a sample data. X Y 1 1 -0.56047565 2 2...
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Dummy and Contrast Codings in R
“Dummy” or “treatment” coding is to create dichotomous variables where each level of the categorical variable is contrasted to a specified reference level. Basic Syntax of Dummy and Contrast Coding 1. Dummy Coding The following is the syntax to do dummy...
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Quartile: Definition and Example
Definition of Quartile A quartile is a statistic describing how a set of data points are divided into 4 groups. Quartiles split a set of data by using 3 points: the lower quartile (Q1), the median (Q2), and the upper...
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Difference between Descriptive Statistics and Inferential Statistics
Descriptive statistics aim to summarize the characteristics of a given data set. In contrast, inferential statistics aim to use a sample of data to draw inferences about the whole population (i.e., hypothesis testing). Types of Descriptive Statistics 1. Measures of Central Tendency...
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Difference between Sample and Population
A population is the entire group of individuals about whom you want to draw conclusions. In contrast, a sample is the subset of the same entire group. Example 1 of sample and population You would like to study if students like...
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Population Variance Formula and Calculation by Hand
This tutorial shows the formula for population variance and the steps for calculating population variance by hand. Formula Population variance is the measure of the variability of a population. The following is the formula for population variance. where, Population vs....
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Sample Variance Formula and Calculation by Hand
Sample variance is the measure of the variability in a given sample. A sample is a set of observations that are a subset of a population. Sample Variance Formula The following is the formula for sample variance. where, Data Example...
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How to Calculate Two-Factor ANOVA without Replication
ANOVA Two-Factor without Replication is used for a design of two factors (e.g., Factor A and Factor B) and only 1 observation in each cell. For instance, both Factor A and Factor B have two levels, leading to 4 cells...
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Difference between ANOVA Two-Factor with Replication and without Replication
You use ANOVA: Two-Factor without Replication when each cell only has 1 observation, but use Two-Factor with Replication when each cell has more than 1 observation. For instance, there are two factors, City and Chain Brand. Each has 2 levels,...
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Difference between Logit and Probit
This tutorial explains the difference between logit and probit in statistics with formulas and examples. Formula and Example for Logit We can start with the following formula. Thus, \( \beta_0+\beta_1x_1+…+\beta_nx_n \) can be from \( -\infty \) to \(+\infty \),...
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