Multiple logistic regression formula example. Logistic Regression - Simple Example.


Multiple logistic regression formula example. Real data can be different than this.


Multiple logistic regression formula example. Real data can be different than this. y^ = β0 +β1x1 +β2x2 + ⋯ +βkxk (14. logistic earlyret bmi sex ib1. Dec 15, 2023 · The following is the regression line plot representing the simple linear regression model discussed in this example: Multiple Linear Regression: Formula of multiple linear regression: y = β0 + β1×1+ β2×2+…+βnxn. How does it do this? It uses a link function to describe a linear relationship between the probability and our independent variables In general, we can have multiple predictor variables in a logistic regression model. In particular, it requires that the outcome variable, y y, is continuous, or Jun 5, 2020 · The standard logistic function is simply the inverse of the logit equation above. Apr 27, 2023 · Logistic regression is a generalized linear model where the outcome is a two-level categorical variable. Jan 8, 2024 · Simple logistic regression finds the equation that best predicts the value of the \(Y\) variable for each value of the \(X\) variable. 4) Dec 20, 2023 · To calculate the Log-Likelihood value, we are going to use the LN function in our dataset. 5) (14. Before we delve into Examples of multinomial logistic regression. , a 1 degree of freedom) predictor variable by including it after the SPSS keyword with . For each training data-point, we have a vector of features, x i, and an observed class, y i. Y = 1 / 1+e -z. Feb 20, 2020 · The formula for a multiple linear regression is: = the predicted value of the dependent variable. The outcome in logistic regression analysis is often coded as 0 or 1, where 1 indicates that the outcome of interest is present, and 0 indicates that the outcome of interest is absent. 2. D. Although the baseline is to identify a binary decision boundary, the approach can be very well applied for scenarios with multiple classification classes or multi-class classification. Nov 21, 2022 · An Intro to Logistic Regression in Python (w/ 100+ Code Examples) The logistic regression algorithm is a probabilistic machine learning algorithm used for classification tasks. OpenIntro Statistics. api: The Standard API. 5 we can take the output as a prediction for the default class (class 0), otherwise the prediction is for the other class (class 1). [1] That is, it is a model that is used to predict the probabilities of the different possible outcomes of a categorically distributed dependent variable May 5, 2019 · At a high level, logistic regression works a lot like good old linear regression. Where Y is a continuous measurement outcome (e. 83) when including stress in the model. It is practically identical to logistic regression, except that you have multiple possible outcomes instead of just one. linear_model import LogisticRegression. 5. where. In Chapter 8, we explore multiple regression, …. 2 A multiple linear regression model. Some extensions like one-vs-rest can allow logistic regression to be used for multi-class classification problems, although they require that the classification problem first be Then, fit your model on the train set using fit () and perform prediction on the test set using predict (). Logistic regression is a GLM used to model a binary categorical variable using numerical and categorical predictors. The occupational choices will be the outcome variable which consists 13. bnXn. Finally, we can fit the logistic regression in Python on our example dataset. 3=University. 75. What makes logistic regression different from linear regression is that you do not measure the \(Y\) variable directly; it is instead the probability of obtaining a particular value of a nominal variable. ) of two classes labeled 0 and 1 representing non-technical and technical article( class 0 is negative class which mean if we get probability less than 0. 9 that this is the case for our simpler_model , but that there are a small number of substantial underestimates in our model. 1. From this analysis, we can see that the odds ratio for conflict_dich decreases a bit (OR=4. a 0 at any value for X are P/(1-P). Let p be the proportion of one outcome, then 1-p will be the proportion of the second outcome. For example, the equation Y represents the formula is equal to a plus bX1 plus cX2 plus dX3 plus E where Y is the dependent variable, and X1, X2, and X3 are independent variables. 2. formula. Nov 27, 2021 · We previously saw that simple linear regression can be extended to multiple linear regression by adding additional independent variables to the right side of the equation, and the same thing can be done in multiple logistic regression. Logistic Regression (aka logit, MaxEnt) classifier. The log odds are then just the natural log (Ln) of the odds. sum earlyret bmi sex educ if pop_logistic ==1. # import the class from sklearn. That is, L(1) = Pr ( y = g | x ). This page uses the following packages. The goal is to determine a mathematical equation that can be used to predict the probability of event 1. We can study the relationship of one’s occupation choice with education level and father’s occupation. The function 𝑝 (𝐱) is often interpreted as the predicted probability that the output for a given 𝐱 is equal to 1. So let’s start with the familiar linear regression equation: Y = B0 + B1*X. The logistic regression model is a generalised linear model with a logit link function, because the linear equation b0 +b1X b 0 + b 1 X predicts the logit of a probability. The formula for Compound Annual Growth rate (CAGR) is = [ (Ending value/Beginning value)^ (1/# of years)] - 1. Step #6: Fit the Logistic Regression Model. Apr 8, 2024 · Multiple regression formulas analyze the relationship between dependent and multiple independent variables. The odds are defined mathematically as P (Y=1) / P (Y=0). Look at various descriptive statistics to get a feel for the data. Binary Logistic Regression. Oct 2, 2020 · Then we can apply this function to the training dataset to output our training feature and target, X and y. This is a binary classification problem because we’re predicting an outcome that can only be one of two values: “yes” or “no”. The fundamental application of logistic regression is to determine a decision boundary for a binary classification problem. Fitted proportional responses are often referred to as event probabilities (i. The algorithm for solving binary classification is logistic regression. From 11,314 under-five children the study considered 36. In cell H5, write done the following formula: =(B5*LN(G5))+((1-B5)*LN(1-G5)) Now, press the Enter key on the keyboard. The categorical response has only two 2 possible outcomes. The outcome, Yi, takes the value 1 (in our application, this represents a spam message) with probability pi and the value 0 with probability 1 − pi. [1] Standard logistic function where. BMTRY 701/755: Biostatistical Methods II Spring 2007 Department of Biostatistics, Bioinformatics and Epidemiology Medical University of South Carolina Lecture 18: Multiple Logistic Regression – p. 5, see the plot of the logistic regression function above for verification. 5) y ^ = β 0 + β 1 x 1 + β 2 x 2 + ⋯ + β k x k. We assume a binomial distribution produced the outcome variable and we therefore want to model p the probability of success for a given set of predictors. The final step in computing the regression coefficient is to find the slope of the relationship between these residuals and UGPA. Insert the dataset from the table Logistic regression fits a linear regression model to the log odds. This equation is indeed very similar to . It can also be used with categorical predictors, and with multiple predictors. When we put them together, their statistical effect on earlyret is mutually adjusted. In the multiclass case, the training algorithm uses the one-vs-rest (OvR) scheme if the ‘multi_class’ option is set to ‘ovr’, and uses the cross-entropy loss if the ‘multi_class’ option is set to ‘multinomial’. For logistic regression, this usually includes looking at descriptive statistics, for example Feb 15, 2014 · Abstract. This step has to be done after the train test split since the scaling calculations are based on the training dataset. Type #1: Binary Logistic Regression. Dec 2, 2020 · Sarah’s GPA is 4. Logistic regression assumes: 1) The outcome is dichotomous; 2) There is a linear relationship between the logit of the outcome and each continuous predictor variable; 3) There are no influential cases/outliers; 4) There is no multicollinearity among the predictors. Mathematically, Odds = p/1-p. A logistic function for health outcomes that occurred or did not occur takes the form shown below. A nursing home has data on N = 284 clients’ sex, age on 1 January 2015 and whether the client passed Oct 28, 2021 · A key difference from linear regression is that the output value being modeled is a binary value (0 or 1) rather than a numeric value. 314 + 0. Specifying a model is done through classes. If the predictor variable female was listed Nov 28, 2021 · I am trying to calculate the variance of the coefficients for logistic regression using bootstrap and I am using scikit-learn and statsmodels to compare results. I am using the following codes to perform the bootstrap: Exercise 8. If we define p as the probability that the outcome is 1, the multiple logistic regression model can be written as follows: Apr 22, 2021 · Multivariate logistic regression model was used to determine the association between stunting, underweight and wasting given that of the estimated effect of other determinants. The result is the impact of each variable on the odds ratio of the observed event of interest. 5 from sigmoid function, it is classified as 0. This logistic function is a simple strategy to map the linear combination “z”, lying in the (-inf,inf) range to the probability interval of [0,1] (in the context of logistic regression, this z will be called the log(odd) or logit or log(p/1-p)) (see the above plot). Apr 23, 2022 · SAT and SAT is necessarily 0. Apr 23, 2022 · David Diez, Christopher Barr, & Mine Çetinkaya-Rundel. 1: s(z)= 1 1+e z = 1 1+exp( z) (5. For example, we could use logistic regression to model the relationship between various measurements of a manufactured specimen (such as dimensions and chemical composition) to predict if a crack greater than 10 Aug 12, 2019 · The logistic regression model takes real-valued inputs and makes a prediction as to the probability of the input belonging to the default class (class 0). k. Examples of ordered logistic regression. 7% of them suffered from stunting, underweight and wasting, respectively. If necessary, refer back to Exercise 8. Binary logistic regression models are a type of logistic regression in which the response variable can only belong to two categories. Examples of mixed effects logistic regression. The first step is to create the tabular structure in Excel for holding your dataset and performing calculations and transformations. 4 and 6. Logistic regression models a relationship between predictor variables and a categorical response variable. May 31, 2016 · Logistic Regression Analysis. Examples of multinomial logistic regression. 2 - Logistic Regression. , the value of the function's midpoint; , the supremum of the values of the function; , the logistic growth rate or steepness of the curve. For example, 3 to 1 odds is another way of saying that the P (Y=1) is 0. Multiple-group discriminant function analysis. Chapter 13 Logistic regression. We often estimate the βi β i parameters using a computer. Linear regression tries to find the best straight line that predicts the outcome from the features. Multinomial logistic regression is used when you have a categorical dependent variable with two or more unordered levels (i. Then, double-click on the Fill Handle icon to determine all log-likelihood values. Linear regression is an excellent choice for analyzing many relationship–but not all of those. In the logit model, the output variable is a Bernoulli random variable (it can take only two values, either 1 or 0) and where is the logistic function, is a vector of inputs and is a vector of coefficients. Apr 27, 2023 · Multiple regression model. However, in logistic regression the output Y is in log odds. when there are k predictors. two or more discrete outcomes). Now we perform a multiple logistic regression analysis with conflict_dich, sex, year, age_cat, qual, stress, and health_dich . Multiple logistic regression can be determined by a stepwise procedure using the step function. Logistic regression. In addition, it assumes that the mean of Yi, μi, is a linear function of all predictors. People have often seen odds used in reference to betting. It is the probability pi that we model in relation to the predictor variables. The logistic function is a sigmoid function, which takes any real input , and outputs a value between zero and one. βj: The coefficient estimate for the jth predictor variable. \) On the LHS of we have the logarithm of the ratio of two probabilities and on the RHS a linear combination of the predictors. The word "linear" in "multiple linear regression" refers to the fact that the model is linear in the parameters, \beta_0, \beta_1, \ldots, \beta_k. If the probability is > 0. ¶. In the formula, y is the dependent variable, x is the independent vector of independent variables, β0 is the intercept, and Oct 27, 2020 · Assumptions of Multiple Linear Regression. p hat n events out of n trials). The occupational choices will be the outcome variable which consists For example, the Pearson residual is a standardized form of residual from logistic regression which can be expected to have a normal distribution over large-enough samples. 2=Upper secondary. This slope is the regression coefficient for HSGPA. Logistic Regression – A Complete Tutorial With Examples in R. , diseased or not diseased). A related technique is multinomial logistic regression which predicts outcome variables with 3+ categories. May 31, 2016 · Logistic regression analysis is a popular and widely used analysis that is similar to linear regression analysis except that the outcome is dichotomous (e. Here, L(1) is the probability that an individual with values x1, x2 ,…, xm is in group g. 1/48 Jun 25, 2020 · Logistic Regression Real Life Example #1. . 4 for additional details about each variable. The multiple logistic regression model is given by the g equations . educ if pop_logistic ==1. 96-5. Its aim is the same as that of all model-building techniques: to derive the best-fitting, most parsimonious (smallest or most efficient), and biologically reasonable Logistic regression estimates the probability of an event occurring, such as voted or didn’t vote, based on a given data set of independent variables. A multivariate method for multinomial outcome variables; Multiple logistic regression analyses, one for each pair of outcomes: One problem with this approach is that each analysis is potentially run on a different sample. The following equation is used to predict HSGPA from SAT: HSGPA ′ = − 1. The parameters of a logistic regression model can be estimated by the probabilistic framework called maximum likelihood estimation. , success/failure, or yes/no, or died/lived). We need to classify Sarah as “yes” or “no” for admission. with more than two possible discrete outcomes. Logistic regression is a predictive modelling algorithm that is used when the Y variable is binary categorical. Jan 6, 2024 · Multivariate regression is a statistical model that predicts multiple dependent variables using two or more independent variables, allowing for a better analysis of interrelated variables through a linear equation. 0036 × SAT. Logistic regression is used to obtain odds ratio in the presence of more than one explanatory variable. If we go from probabilities to log-odds, we use the logit function, logit(p) = ln p 1−p logit ( p) = ln p 1 − p. Value labels. If \(J=2,\) it is the same up to a change in the codes for the levels: the logistic regression giving the probability of \(Y=1\) versus \(Y=2. If we have 2 classes, we use the logistic sigmoid function to transform our linear function into probabilities. Logistic regression is a discriminative classifier. Sigmoid function. log (p/1-p) = β0 + β1x. LogisticRegression. For example, children’s food choices are influenced by their Logistic regression is a twist on regression for categorical/class target variables, where instead of solving for the mean of y, logistic regression solves for the probability of class membership of y. In some cases, it makes sense to “factor” the response into a sequence of binary choices and model them with a sequence of ordinary logistic models. Under this framework, a probability distribution for the target variable (class label) must be assumed and then a likelihood function defined that calculates the probability of observing 12. 3 and her exam score is 79. Here are a couple examples: Example 1: NBA Draft Multiple logistic regression is distinguished from multiple linear regression in that the outcome variable (dependent variables) is dichotomous (e. Example 1. Solution. Medical researchers want to know how exercise and weight impact the probability of having a heart attack. g. A logistic regression is typically used when there is one dichotomous outcome variable (such as winning or losing), and a continuous predictor variable which is related to the probability or odds of the outcome variable. y is the predicted output. The sigmoid function also called a logistic function. Apr 12, 2021 · There are multiple types of logistic regression: There is binary logistic regression which aims to predict one of two classes, multinomial logistic regression where instead of predicting one of And as with simple linear regression, the regression can be summarized with a mathematical equation. The logistic function is a type of sigmoid function. Data gets separated into explanatory variables ( exog) and a response variable ( endog ). The statistical model for logistic regression is. # instantiate the model (using the default parameters) logreg = LogisticRegression ( random_state =16) # fit the model with data. Logit = log odds = log (π/ (1-π)) When a logistic regression model has been fitted, estimates of π are marked with a hat symbol above the Greek letter pi to denote that the proportion is estimated from the fitted regression model. Chapter 13. Similar to a simple linear regression model, a multiple linear regression model assumes a observation specific mean μi for the i -th response variable Yi . 3 Odds Ratios and Logistic Regression Output. The goal of Lecture 18: Multiple Logistic Regression Mulugeta Gebregziabher, Ph. 5 Diagnostics for Multiple Logistic Regression. Mar 15, 2018 · This justifies the name ‘logistic regression’. This function selects models to minimize AIC, not according to p-values as does the SAS example in the Handbook . The sigmoid has the following equation, function shown graphically in Fig. This simply means that each parameter multiplies an x -variable, while the regression function is a sum of these "parameter times x -variable" terms. 12. the effect that increasing the value of the independent variable has on the predicted y value Mar 31, 2021 · Logistic Function (Image by author) Hence the name logistic regression. A multiple regression model is a linear model with many predictors. In Chapter 8, we explore multiple regression, which introduces the possibility of more than one predictor, and logistic regression, a technique for predicting Mar 27, 2023 · Summary. Oct 27, 2020 · Logistic regression uses a method known as maximum likelihood estimation (details will not be covered here) to find an equation of the following form: log [p (X) / (1-p (X))] = β0 + β1X1 + β2X2 + … + βpXp. As such, it’s often close to either 0 or 1. Since the outcome is a probability, the dependent variable is bounded Jun 8, 2020 · The odds are simply calculated as a ratio of proportions of two possible outcomes. OpenAI. b0 is the bias or intercept term. I am assuming that you already know how to implement a binary classification with Logistic Regression. The probability of that class was either p, if y i =1, or 1− p, if y i =0. We can see in Figure 5. If we solve for p from the logit equation, the formula of the logistic function is below: p = 1/ (1 + e^ (- (w0 + w1*x1 + w2*x2 + … + wm*xm))) where e is the base of the natural logarithms. In this model, we have three x-variables: bmi, sex, and educ. Logistic Regression - Simple Example. Jan 12, 2021 · This video presents the model equation for logistic regression. Dec 26, 2017 · We implement logistic regression using Excel for classification. The formula on the right side of An explanation of logistic regression can begin with an explanation of the standard logistic function. It takes the time to build it up step by step, providing an explanation of what it is and wh Logistic regression models a relationship between predictor variables and a categorical response variable. = the y-intercept (value of y when all other parameters are set to 0) = the regression coefficient () of the first independent variable () (a. The sigmoid function (named because it looks like an s) is also called the logistic func-logistic tion, and gives logistic regression its name. It forms an equation like. A is the intercept, b, c, and d are the slopes, and E is May 19, 2020 · May 19, 2020. For values of in the domain of real numbers from to , the S Describing polytomous responses by a sequence of binary models. There are four key assumptions that multiple linear regression makes about the data: 1. I am using the Default dataset from the ISLR website which can be found in the zip forlder here or here as a plain csv file. That is, it can take only two values like 1 or 0. The likelihood sigmoid To create a probability, we’ll pass z through the sigmoid function, s(z). Logistic regression, by default, is limited to two-class classification problems. Furthermore, The vector of coefficients is the parameter to be estimated by maximum likelihood. This article will focus on the implementation of logistic regression for multiclass classification problems. The validity and reliability of such a model rely upon the assumptions of independence, linearity, normality, and homoscedasticity. The logistic regression function 𝑝 (𝐱) is the sigmoid function of 𝑓 (𝐱): 𝑝 (𝐱) = 1 / (1 + exp (−𝑓 (𝐱)). Logit Regression | R Data Analysis Examples. Sep 1, 2020 · Multinomial logistic regression is an extension of logistic regression that adds native support for multi-class classification problems. If P is the probability of a 1 at for given value of X, the odds of a 1 vs. Note, also, that in this example the step function found a different model than did the procedure in the Handbook. Step-by-step guide Oct 28, 2019 · Logistic regression is a model for binary classification predictive modeling. Apr 4, 2024 · Types of Logistic Regression Binary logistic regression. Unlike many machine learning algorithms that seem to be a black box, the logisitc Feb 21, 2019 · The logistic regression classifier will predict “Male” if: This is because the logistic regression “ threshold ” is set at g (z)=0. Example: Spam or Not. 1 Likelihood Function for Logistic Regression Because logistic regression predicts probabilities, rather than just classes, we can fit it using likelihood. 1. For example, consider the study of the effects of radiation exposure on mortality. This type of statistical model (also known as logit model) is often used for classification and predictive analytics. linear_model. 88). Now Logistic regression with many variables Logistic regression with interaction terms In all cases, we will follow a similar procedure to that followed for multiple linear regression: 1. Usually x1 = 1 (that is, an intercept is included), but this is not necessary. a. The occupational choices will be the outcome variable which consists Examples of multinomial logistic regression. We assume that the estimation is carried Aug 6, 2021 · This tutorial provides a brief explanation of each type of logistic regression model along with examples of each. 000; CI= 3. This is usually the first classification algorithm you'll try a classification task on. The predictor variable female is coded 0 = male and 1 = female. Jan 26, 2024 · Step 1: Insert Historical Data and Regression Coefficients. Example 1: A researcher sampled applications to 40 different colleges to study factor that predict admittance into college. Logistic regression is a classification model. Predictors include student’s high school GPA, extracurricular activities, and SAT scores. In linear regression, the output Y is in the same units as the target variable (the thing you are trying to predict). In his example the ending value would be the population after 20 years and the beginning value is the initial population. For our data set the values of θ are: To get access to the θ parameters computed by scikit-learn one can do: # For theta_0: print 11. In Section 11. Here is an example of a logistic regression equation: y = e^ (b0 + b1*x) / (1 + e^ (b0 + b1*x)) Where: x is the input value. In general, we write the model as. Apr 28, 2023 · 14: Multiple and Logistic Regression. Independence: The residuals are independent. We use logistic regression when the dependent variable is categorical. People’s occupational choices might be influenced by their parents’ occupations and their own education level. Make sure that you can load them before trying to run Sep 5, 2020 · Logistic regression is a very popular machine learning technique. Introduction to Binary Logistic Regression 3 Introduction to the mathematics of logistic regression Logistic regression forms this model by creating a new dependent variable, the logit(P). Selva Prabhakaran. Logistic regression, also called a logit model, is used to model dichotomous outcome variables. The softmax function is the generalisation of the logistic sigmoid function to multiple classes. where: Xj: The jth predictor variable. Data is fit into linear regression model, which then be acted upon by a logistic function predicting the target categorical dependent variable. In the logit model the log odds of the outcome is modeled as a linear combination of the predictor variables. The principles of simple linear regression lay the foundation for more sophisticated regression methods used in a wide range of challenging settings. These factors may include what type of sandwich is ordered (burger or chicken), whether or not fries are also ordered, and age of Logistic regression finds the best possible fit between the predictor and target variables to predict the probability of the target variable belonging to a labeled class/category. The information in the preceding section is the basis for interpreting output from logistic regression; Odds ratios are derived from the output; MUST know how your variables are coded; The process is more or less the same with linear regression Plug in values of X into the equation; Covert to This analysis is also known as binary logistic regression or simply “logistic regression”. Use the regression table below to answer the following questions. For example, we could use logistic regression to model the relationship between various measurements of a manufactured specimen (such as dimensions and chemical composition) to predict if a crack greater than 10 mils will occur (a binary variable: either yes or no). 1=Compulsory. A logistic function or logistic curve is a common S-shaped curve ( sigmoid curve) with the equation. , BMI), b 0 is the "intercept" or starting value. sklearn. . Types of Logistic Regression. e. The procedure is quite similar to multiple linear regression, with the exception that the response variable is binomial. api: The Formula API. Some schools are more or less selective, so the baseline probability of admittance Before starting, it's worth mentioning there are two ways to do Logistic Regression in statsmodels: statsmodels. Y = b0 + b1X1 + b2X2 + b3X3 . 4 considers a model that predicts the number of days absent using three predictors: ethnic background (eth), gender (sex), and learner status (lrn). So, if the value of z goes to positive infinity then the predicted value of y will become 1 and if it goes to We will use the nomreg command to run the multinomial logistic regression. We create a hypothetical example (assuming technical article requires more time to read. An equation for multiple linear regression has the general form shown below. Binary logistic regression is used to predict the probability of a binary outcome, such as yes or no, true or false, or 0 or 1. logit(p) = log(p/(1-p))= β 0 + β 1 *x1 + … + β k *xk Applying such a model to our example dataset, each estimated coefficient is the expected change in the log odds of being in an honors class for a unit increase in the corresponding predictor variable It is a mathematical function having a characteristic that can take any real value and map it to between 0 to 1 shaped like the letter “S”. The logit(P) Dec 20, 2023 · Multiple Linear Regression - MLR: Multiple linear regression (MLR) is a statistical technique that uses several explanatory variables to predict the outcome of a response variable. The earlier discussion in this module provided a demonstration of how regression analysis can provide control of confounding for multiple In statistics, multinomial logistic regression is a classification method that generalizes logistic regression to multiclass problems, i. statsmodels. [2] For the logit, this is interpreted as taking input log-odds and having output probability. β 0, β 1, …, β k. However, the association is still significant (P=0. The response variable in the model will be 4 days ago · Multiple Logistic Regression Model the relationship between a categorial response variable and two or more continuous or categorical explanatory variables. Example 1: A marketing research firm wants to investigate what factors influence the size of soda (small, medium, large or extra large) that people order at a fast-food chain. To understand the relationship between the predictor variables and the probability of having a heart attack, researchers can perform logistic regression. In the analysis below, we treat the variable female as a continuous (i. 3 we introduced linear regression, one of the most widely used tool to analyze relationships. In a new Excel sheet, create four columns labeled ““Points,” “Rebounds,” “Assists,” and “Drafted?”. 2, 21. Logistic Regression. 14. For example, it could be used to predict whether a customer will churn or not, whether a patient has a disease or not, or whether a loan will be repaid or not. Yi ∣ μi, σind ∼ Normal(μi, σ), i = 1, ⋯, n. Linear relationship: There exists a linear relationship between the independent variable, x, and the dependent variable, y. uw ph cw du oi ba bb qs sf yq