1 Simple Linear Regression I – Least Squares Estimation
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Companhia Brasileira De Distribuição Material Fact
COMPANHIA BRASILEIRA DE DISTRIBUIÇÃO PUBLICLY-HELD COMPANY WITH AUTHORIZED CAPITAL CNPJ/ME No. 47.508.411/0001-56 NIRE 35.300.089.901 MATERIAL FACT Companhia Brasileira de Distribuição (“Company” or “GPA”), in accordance with article 157 of Law 6,404/76 and CVM Instruction No. 358/02, hereby informs its shareholders and the market in general that its Board of Directors, at the meeting held on this date, approved initiating a study to segregate its cash and carry unit through a partial spin-off of the Company and its wholly owned subsidiary Sendas Distribuidora S.A. (“Assaí” and the “Spin-off”, respectively). The Spin-off will be preceded by the transfer of the shareholding interest currently held by Assaí in Almacenes Éxito S.A. to GPA (the Spin-off, together with the preceding transfer aforementioned, the “Potential Transaction”). The goal of the Potential Transaction is to unleash the full potential of the Company’s cash & carry and traditional retail businesses, allowing them to operate on a standalone basis, with separate management teams, and focusing on their respective businesses models and market opportunities. Additionally, the Potential Transaction will provide each of the businesses with direct access to the capital markets and other sources of funding, hence allowing them to prioritize investments according to each company’s profile, thus creating more value for their respective shareholders. Upon the implementation of the Potential Transaction, the shares issued by Assaí and held by the Company will be distributed to the Company’s shareholders, on a pro rata basis. The distribution of shares will occur after the listing of Assaí’s shares on the Novo Mercado segment of B3 S.A. -
Chapter 2 Time Series and Forecasting
Chapter 2 Time series and Forecasting 2.1 Introduction Data are frequently recorded at regular time intervals, for instance, daily stock market indices, the monthly rate of inflation or annual profit figures. In this Chapter we think about how to display and model such data. We will consider how to detect trends and seasonal effects and then use these to make forecasts. As well as review the methods covered in MAS1403, we will also consider a class of time series models known as autore- gressive moving average models. Why is this topic useful? Well, making forecasts allows organisations to make better decisions and to plan more efficiently. For instance, reliable forecasts enable a retail outlet to anticipate demand, hospitals to plan staffing levels and manufacturers to keep appropriate levels of inventory. 2.2 Displaying and describing time series A time series is a collection of observations made sequentially in time. When observations are made continuously, the time series is said to be continuous; when observations are taken only at specific time points, the time series is said to be discrete. In this course we consider only discrete time series, where the observations are taken at equal intervals. The first step in the analysis of time series is usually to plot the data against time, in a time series plot. Suppose we have the following four–monthly sales figures for Turner’s Hangover Cure as described in Practical 2 (in thousands of pounds): Jan–Apr May–Aug Sep–Dec 2006 8 10 13 2007 10 11 14 2008 10 11 15 2009 11 13 16 We could enter these data into a single column (say column C1) in Minitab, and then click on Graph–Time Series Plot–Simple–OK; entering C1 in Series and then clicking OK gives the graph shown in figure 2.1. -
Demand Forecasting
BIZ2121 Production & Operations Management Demand Forecasting Sung Joo Bae, Associate Professor Yonsei University School of Business Unilever Customer Demand Planning (CDP) System Statistical information: shipment history, current order information Demand-planning system with promotional demand increase, and other detailed information (external market research, internal sales projection) Forecast information is relayed to different distribution channel and other units Connecting to POS (point-of-sales) data and comparing it to forecast data is a very valuable ways to update the system Results: reduced inventory, better customer service Forecasting Forecasts are critical inputs to business plans, annual plans, and budgets Finance, human resources, marketing, operations, and supply chain managers need forecasts to plan: ◦ output levels ◦ purchases of services and materials ◦ workforce and output schedules ◦ inventories ◦ long-term capacities Forecasting Forecasts are made on many different variables ◦ Uncertain variables: competitor strategies, regulatory changes, technological changes, processing times, supplier lead times, quality losses ◦ Different methods are used Judgment, opinions of knowledgeable people, average of experience, regression, and time-series techniques ◦ No forecast is perfect Constant updating of plans is important Forecasts are important to managing both processes and supply chains ◦ Demand forecast information can be used for coordinating the supply chain inputs, and design of the internal processes (especially -
Generalized Linear Models and Generalized Additive Models
00:34 Friday 27th February, 2015 Copyright ©Cosma Rohilla Shalizi; do not distribute without permission updates at http://www.stat.cmu.edu/~cshalizi/ADAfaEPoV/ Chapter 13 Generalized Linear Models and Generalized Additive Models [[TODO: Merge GLM/GAM and Logistic Regression chap- 13.1 Generalized Linear Models and Iterative Least Squares ters]] [[ATTN: Keep as separate Logistic regression is a particular instance of a broader kind of model, called a gener- chapter, or merge with logis- alized linear model (GLM). You are familiar, of course, from your regression class tic?]] with the idea of transforming the response variable, what we’ve been calling Y , and then predicting the transformed variable from X . This was not what we did in logis- tic regression. Rather, we transformed the conditional expected value, and made that a linear function of X . This seems odd, because it is odd, but it turns out to be useful. Let’s be specific. Our usual focus in regression modeling has been the condi- tional expectation function, r (x)=E[Y X = x]. In plain linear regression, we try | to approximate r (x) by β0 + x β. In logistic regression, r (x)=E[Y X = x] = · | Pr(Y = 1 X = x), and it is a transformation of r (x) which is linear. The usual nota- tion says | ⌘(x)=β0 + x β (13.1) · r (x) ⌘(x)=log (13.2) 1 r (x) − = g(r (x)) (13.3) defining the logistic link function by g(m)=log m/(1 m). The function ⌘(x) is called the linear predictor. − Now, the first impulse for estimating this model would be to apply the transfor- mation g to the response. -
Moving Average Filters
CHAPTER 15 Moving Average Filters The moving average is the most common filter in DSP, mainly because it is the easiest digital filter to understand and use. In spite of its simplicity, the moving average filter is optimal for a common task: reducing random noise while retaining a sharp step response. This makes it the premier filter for time domain encoded signals. However, the moving average is the worst filter for frequency domain encoded signals, with little ability to separate one band of frequencies from another. Relatives of the moving average filter include the Gaussian, Blackman, and multiple- pass moving average. These have slightly better performance in the frequency domain, at the expense of increased computation time. Implementation by Convolution As the name implies, the moving average filter operates by averaging a number of points from the input signal to produce each point in the output signal. In equation form, this is written: EQUATION 15-1 Equation of the moving average filter. In M &1 this equation, x[ ] is the input signal, y[ ] is ' 1 % y[i] j x [i j ] the output signal, and M is the number of M j'0 points used in the moving average. This equation only uses points on one side of the output sample being calculated. Where x[ ] is the input signal, y[ ] is the output signal, and M is the number of points in the average. For example, in a 5 point moving average filter, point 80 in the output signal is given by: x [80] % x [81] % x [82] % x [83] % x [84] y [80] ' 5 277 278 The Scientist and Engineer's Guide to Digital Signal Processing As an alternative, the group of points from the input signal can be chosen symmetrically around the output point: x[78] % x[79] % x[80] % x[81] % x[82] y[80] ' 5 This corresponds to changing the summation in Eq. -
Time Series and Forecasting
Time Series and Forecasting Time Series • A time series is a sequence of measurements over time, usually obtained at equally spaced intervals – Daily – Monthly – Quarterly – Yearly 1 Time Series Example Dow Jones Industrial Average 12000 11000 10000 9000 Closing Value Closing 8000 7000 1/3/00 5/3/00 9/3/00 1/3/01 5/3/01 9/3/01 1/3/02 5/3/02 9/3/02 1/3/03 5/3/03 9/3/03 Date Components of a Time Series • Secular Trend –Linear – Nonlinear • Cyclical Variation – Rises and Falls over periods longer than one year • Seasonal Variation – Patterns of change within a year, typically repeating themselves • Residual Variation 2 Components of a Time Series Y=T+C+S+Rtt tt t Time Series with Linear Trend Yt = a + b t + et 3 Time Series with Linear Trend AOL Subscribers 30 25 20 15 10 5 Number of Subscribers (millions) 0 2341234123412341234123 1995 1996 1997 1998 1999 2000 Quarter Time Series with Linear Trend Average Daily Visits in August to Emergency Room at Richmond Memorial Hospital 140 120 100 80 60 40 Average Daily Visits Average Daily 20 0 12345678910 Year 4 Time Series with Nonlinear Trend Imports 180 160 140 120 100 80 Imports (MM) Imports 60 40 20 0 1986 1988 1990 1992 1994 1996 1998 Year Time Series with Nonlinear Trend • Data that increase by a constant amount at each successive time period show a linear trend. • Data that increase by increasing amounts at each successive time period show a curvilinear trend. • Data that increase by an equal percentage at each successive time period can be made linear by applying a logarithmic transformation. -
Penalised Regressions Vs. Autoregressive Moving Average Models for Forecasting Inflation Regresiones Penalizadas Vs
ECONÓMICAS . Ospina-Holguín y Padilla-Ospina / Económicas CUC, vol. 41 no. 1, pp. 65 -80, Enero - Junio, 2020 CUC Penalised regressions vs. autoregressive moving average models for forecasting inflation Regresiones penalizadas vs. modelos autorregresivos de media móvil para pronosticar la inflación DOI: https://doi.org/10.17981/econcuc.41.1.2020.Econ.3 Abstract This article relates the Seasonal Autoregressive Moving Average Artículo de investigación. Models (SARMA) to linear regression. Based on this relationship, the Fecha de recepción: 07/10/2019. paper shows that penalized linear models can outperform the out-of- Fecha de aceptación: 10/11/2019. sample forecast accuracy of the best SARMA models in forecasting Fecha de publicación: 15/11/2019 inflation as a function of past values, due to penalization and cross- validation. The paper constructs a minimal functional example using edge regression to compare both competing approaches to forecasting monthly inflation in 35 selected countries of the Organization for Economic Cooperation and Development and in three groups of coun- tries. The results empirically test the hypothesis that penalized linear regression, and edge regression in particular, can outperform the best standard SARMA models calculated through a grid search when fore- casting inflation. Thus, a new and effective technique for forecasting inflation based on past values is provided for use by financial analysts and investors. The results indicate that more attention should be paid Javier Humberto Ospina-Holguín to automatic learning techniques for forecasting inflation time series, Universidad del Valle. Cali (Colombia) even as basic as penalized linear regressions, because of their superior [email protected] empirical performance. -
Aviso De Derechos Para Emisoras Del SIC
Aviso de Derechos para emisoras del SIC FECHA: 08/03/2021 BOLSA MEXICANA DE VALORES, S.A.B DE C.V, INFORMA: FOLIO DE REFERENCIA DEL EVENTO CORPORATIVO 137412 FOLIO DE REFERENCIA INDEVAL 259318C004 TIPO DE MENSAJE Replace COMPLETO / INCOMPLETO COMPLETE CONFIRMADO / NO CONFIRMADO CONFIRMED CLAVE DE COTIZACIÓN CBD RAZÓN SOCIAL COMPANHIA BRASILEIRA DE DISTRIBUICAO GRUPO PAO DE ACUCAR SERIE N ISIN US20440T3005 MERCADO PRINCIPAL NEW YORK STOCK EXCHANGE TIPO DE EVENTO SPIN-OFF MANDATORIO / OPCIONAL / VOLUNTARIO Mandatory FECHA EXDATE 08/03/2021 FECHA REGISTRO 02/03/2021 DUE BILL OFF DATE 09/03/2021 OPCIÓN 1 TIPO Security DEFAULT true TRANSACCIÓN Cash Movement CREDIT / DEBIT Debit FECHA DE PAGO 05/03/2021 Bolsa Mexicana de Valores S.A.B. de C.V. 1 Aviso de Derechos para emisoras del SIC FECHA: 08/03/2021 FEE USD 0.03 TRANSACCIÓN Securities Movement CREDIT / DEBIT Credit FECHA DE PAGO 05/03/2021 AdditionalQuantityForExistingSecurities RATIO 1 / 1 NewIssue VALORES A RECIBIR US81689T1043 NOTAS DEL EVENTO CORPORATIVO NOTA (24/02/2021) Companhia Brasileira de Distribuicao – Distribution Symbol: CBD Companhia Brasileira de Distribuicao (CBD) has announced a distribution of (New) Sendas Distribuidora S.A. (ASAI) American Depositary Shares. The distribution ratio is 1.0 of an ASAI share for each CBD share held. The NYSE has set March 8, 2021, as the ex-distribution date for this distribution. Sendas Distribuidora S.A. American Depositary Shares will begin trading on a when issued basis on March 1, 2021 on the NYSE under the trading symbol “ASAI WI” and are anticipated to begin trading regular way on March 8, 2021, under the trading symbol “ASAI”. -
Generalized and Weighted Least Squares Estimation
LINEAR REGRESSION ANALYSIS MODULE – VII Lecture – 25 Generalized and Weighted Least Squares Estimation Dr. Shalabh Department of Mathematics and Statistics Indian Institute of Technology Kanpur 2 The usual linear regression model assumes that all the random error components are identically and independently distributed with constant variance. When this assumption is violated, then ordinary least squares estimator of regression coefficient looses its property of minimum variance in the class of linear and unbiased estimators. The violation of such assumption can arise in anyone of the following situations: 1. The variance of random error components is not constant. 2. The random error components are not independent. 3. The random error components do not have constant variance as well as they are not independent. In such cases, the covariance matrix of random error components does not remain in the form of an identity matrix but can be considered as any positive definite matrix. Under such assumption, the OLSE does not remain efficient as in the case of identity covariance matrix. The generalized or weighted least squares method is used in such situations to estimate the parameters of the model. In this method, the deviation between the observed and expected values of yi is multiplied by a weight ω i where ω i is chosen to be inversely proportional to the variance of yi. n 2 For simple linear regression model, the weighted least squares function is S(,)ββ01=∑ ωii( yx −− β0 β 1i) . ββ The least squares normal equations are obtained by differentiating S (,) ββ 01 with respect to 01 and and equating them to zero as nn n ˆˆ β01∑∑∑ ωβi+= ωiixy ω ii ii=11= i= 1 n nn ˆˆ2 βω01∑iix+= βω ∑∑ii x ω iii xy. -
18.650 (F16) Lecture 10: Generalized Linear Models (Glms)
Statistics for Applications Chapter 10: Generalized Linear Models (GLMs) 1/52 Linear model A linear model assumes Y X (µ(X), σ2I), | ∼ N And ⊤ IE(Y X) = µ(X) = X β, | 2/52 Components of a linear model The two components (that we are going to relax) are 1. Random component: the response variable Y X is continuous | and normally distributed with mean µ = µ(X) = IE(Y X). | 2. Link: between the random and covariates X = (X(1),X(2), ,X(p))⊤: µ(X) = X⊤β. · · · 3/52 Generalization A generalized linear model (GLM) generalizes normal linear regression models in the following directions. 1. Random component: Y some exponential family distribution ∼ 2. Link: between the random and covariates: ⊤ g µ(X) = X β where g called link function� and� µ = IE(Y X). | 4/52 Example 1: Disease Occuring Rate In the early stages of a disease epidemic, the rate at which new cases occur can often increase exponentially through time. Hence, if µi is the expected number of new cases on day ti, a model of the form µi = γ exp(δti) seems appropriate. ◮ Such a model can be turned into GLM form, by using a log link so that log(µi) = log(γ) + δti = β0 + β1ti. ◮ Since this is a count, the Poisson distribution (with expected value µi) is probably a reasonable distribution to try. 5/52 Example 2: Prey Capture Rate(1) The rate of capture of preys, yi, by a hunting animal, tends to increase with increasing density of prey, xi, but to eventually level off, when the predator is catching as much as it can cope with. -
Simple Linear Regression with Least Square Estimation: an Overview
Aditya N More et al, / (IJCSIT) International Journal of Computer Science and Information Technologies, Vol. 7 (6) , 2016, 2394-2396 Simple Linear Regression with Least Square Estimation: An Overview Aditya N More#1, Puneet S Kohli*2, Kshitija H Kulkarni#3 #1-2Information Technology Department,#3 Electronics and Communication Department College of Engineering Pune Shivajinagar, Pune – 411005, Maharashtra, India Abstract— Linear Regression involves modelling a relationship amongst dependent and independent variables in the form of a (2.1) linear equation. Least Square Estimation is a method to determine the constants in a Linear model in the most accurate way without much complexity of solving. Metrics where such as Coefficient of Determination and Mean Square Error is the ith value of the sample data point determine how good the estimation is. Statistical Packages is the ith value of y on the predicted regression such as R and Microsoft Excel have built in tools to perform Least Square Estimation over a given data set. line The above equation can be geometrically depicted by Keywords— Linear Regression, Machine Learning, Least Squares Estimation, R programming figure 2.1. If we draw a square at each point whose length is equal to the absolute difference between the sample data point and the predicted value as shown, each of the square would then represent the residual error in placing the I. INTRODUCTION regression line. The aim of the least square method would Linear Regression involves establishing linear be to place the regression line so as to minimize the sum of relationships between dependent and independent variables. -
4.3 Least Squares Approximations
218 Chapter 4. Orthogonality 4.3 Least Squares Approximations It often happens that Ax D b has no solution. The usual reason is: too many equations. The matrix has more rows than columns. There are more equations than unknowns (m is greater than n). The n columns span a small part of m-dimensional space. Unless all measurements are perfect, b is outside that column space. Elimination reaches an impossible equation and stops. But we can’t stop just because measurements include noise. To repeat: We cannot always get the error e D b Ax down to zero. When e is zero, x is an exact solution to Ax D b. When the length of e is as small as possible, bx is a least squares solution. Our goal in this section is to compute bx and use it. These are real problems and they need an answer. The previous section emphasized p (the projection). This section emphasizes bx (the least squares solution). They are connected by p D Abx. The fundamental equation is still ATAbx D ATb. Here is a short unofficial way to reach this equation: When Ax D b has no solution, multiply by AT and solve ATAbx D ATb: Example 1 A crucial application of least squares is fitting a straight line to m points. Start with three points: Find the closest line to the points .0; 6/; .1; 0/, and .2; 0/. No straight line b D C C Dt goes through those three points. We are asking for two numbers C and D that satisfy three equations.