Free Essay

Linear Regression

In:

Submitted By IMNAvenger
Words 717
Pages 3
Linear Regression Forecast
Nicolas Scott Gomez
Park University

Introduction………………………………………………………………………………………..3
Subjects and Methods...…………………..…………………………….…………………………3
Results…………………..…………………………………………………………………………4
References…...…………………………………………………………………………………….7

Introduction
There is a growing awareness of obesity in more modern nations which has added importance to efforts in understanding causes and natural history of obesity. In order to understand it, you must determine what a normal body fat content is and how it changes with age. Most recently, there are four component models of body composition that don’t rely on major assumptions about constant compositions that have been developed. The models offer the opportunity to determine the relation between age and body composition components such as fat in a more accurate way. In 1999, a study was done showing several studies showing body composition variables like fat mass and how they vary significantly among ethnic groups.
Subjects and Methods
Fat mass was determined once in a large sample of healthy volunteers by using a 4 component model requiring measurement of body volume, total body water, total body bone mineral mass and the body weight. The relation between age and body fat was explored by using several different statistical methods and the 1324 volunteers ages 20-94 were recruited for his study through various means of advertising. These studies were performed between 1986 and 1997 and each potential subject needed to have all four grandparents while also being screened with a medical history questionnaire and brief physical exam.
Each subject fasted overnight and a body weight was measured to + 0.2 kg by using a standard balance scale and measured to + 0.5 cm and all the measurements were completed on the same day.
Body density and volume were determined by using a specific method where each subject wore a bathing suit and performed 5-10 submersions with maximum exhalations. Total body fat was calculated in all subjects by using a 4 component model requiring measurements of body volume, TBW, TBBM and body weight. This method provides estimates of body fat that are independent of major age, sex and ethnicity related assumptions by using the equation: Fat mass = (2.513 x body volume) – (.739 x TBW) + (.947 x TBBM) – (1.79 x body weight). This equation is estimated to be 1.6% of body weight.
Subjects were also divided into age groups by decade and the mean and standard deviation of fat mass and fat percentage for each age group were calculated. The linear regression analysis was also performed independently for each ethnic and sex group and coefficients were compared across groups and for fat mass, this analysis was performed both with and without adjustment for body size.
Results
Number of subjects by age, sex, and ethnicity | | Age | | 20–29 y | 30–39 y | 40–49 y | 50–59 y | 60–69 y | 70–79 y | ≥80 y | All ages | Women | | | | | | | | | Asian | 17 | 22 | 16 | 21 | 31 | 9 | 4 | 120 | Black | 16 | 36 | 31 | 31 | 27 | 15 | 6 | 162 | Puerto Rican | 17 | 19 | 15 | 25 | 15 | 6 | 1 | 98 | White | 56 | 73 | 47 | 70 | 55 | 44 | 15 | 360 | Men | | | | | | | | | Asian | 17 | 14 | 15 | 16 | 25 | 14 | 1 | 102 | Black | 18 | 24 | 29 | 20 | 17 | 15 | 2 | 125 | Puerto Rican | 17 | 20 | 22 | 24 | 21 | 7 | 0 | 111 | White | 40 | 61 | 36 | 41 | 33 | 22 | 13 | 246 | Total | 198 | 269 | 211 | 248 | 224 | 132 | 42 | 1324 |

The above tables are the number of subjects in each sex, ethnic and age group and to determine how representative the sample was, the body mass index of subjects was compared. The subjects in the study tended to have a lower mean BMI but in both populations, the relation between age and BMI was similar. There was a low BMI in the youngest groups, relatively high BMI in middle-aged people and a progressively lower BMI in older age groups. Most investigations believe body fat increases from young adulthood to middle age and the relation between age and body fat in older individuals is less clear.

References
What is linear regression. (n.d.). Retrieved from http://www.investorwords.com/2829/linear_regression.html
Mott, J. W., Wang, J., Thornton, J. C., Allison, D. B., Heymsfield, S. B., & Pierson Jr, R. N. (1999). Relation between body fat and age in 4 ethnic groups. Retrieved from http://ajcn.nutrition.org/content/69/5/1007.full

Similar Documents

Premium Essay

Linear Regression

...Linear Regression I would like to know if people who enjoy thrill seeking have tattoos. I believe thrill seeking and tattoos go hand in hand. Most people I know are adventurous, risk takers, and daredevils and all of them have tattoos. I have a strong feeling that the correlation between the two will have a strong positive relationship. X= Tattoos Y= Thrill Seeking The scatter plot shows an extremely rough linear pattern but there is an upward sloping. Line of best fit: y = 0.9148x +25.505 Analysis: 1. r = .14 little or no correlation 2. R^2 = 2% 2% of the variance in thrill seeking is accounted by tattoos. 3. Slope = 0.0196(m) For every 1 tattoo people have there is an increase we expected of 0.9148 in thrill seeking. Conclusion: Between these two variables, there are no correlations between the two. It was shocking to see there is no relationship between the two. I truly believed people who are thrill seekers have tattoo. T-Test Independent 2 Sample My gym teacher believes that males are stronger than females and that is why males have more tattoos. The scale is determine by the number of tattoos both males and females have. Eighty-four males and one hundred and eleven females responded. The males average 39 (s.d. 1.42) while the females average 38 (s.d. 0.98). At the .10 significance level, test to see if there is a difference between males having more tattoos than females? Ho: Null Hypothesis Males equal Females Ha: Null Hypothesis...

Words: 478 - Pages: 2

Premium Essay

Linear Regression

...Linear Regression deals with the numerical measures to express the relationship between two variables. Relationships between variables can either be strong or weak or even direct or inverse. A few examples may be the amount McDonald’s spends on advertising per month and the amount of total sales in a month. Additionally the amount of study time one puts toward this statistics in comparison to the grades they receive may be analyzed using the regression method. The formal definition of Regression Analysis is the equation that allows one to estimate the value of one variable based on the value of another. Key objectives in performing a regression analysis include estimating the dependent variable Y based on a selected value of the independent variable X. To explain, Nike could possibly measurer how much they spend on celebrity endorsements and the affect it has on sales in a month. When measuring, the amount spent celebrity endorsements would be the independent X variable. Without the X variable, Y would be impossible to estimate. The general from of the regression equation is Y hat "=a + bX" where Y hat is the estimated value of the estimated value of the Y variable for a selected X value. a represents the Y-Intercept, therefore, it is the estimated value of Y when X=0. Furthermore, b is the slope of the line or the average change in Y hat for each change of one unit in the independent variable X. Finally, X is any value of the independent variable that is selected. Regression...

Words: 1324 - Pages: 6

Premium Essay

Multiple Linear Regression

...In multiple linear regression analysis, R2 is a measure of the ________. A) homoskedasticity of the predictors B) misclassification rate C) percentage of the variance of the dependent variable that is explained by the set of independent (predictor) variables D) precision of the resulting model when applied to the validation data 2. Categorical variables can be used in a multiple linear regression model _________. A) by partitioning of the dataset B) when no multicollinearity among the independent variables is present C) when the sample size is at least 10 times that of the number of variables D) through the use of dummy variables 3. In multiple linear regression analysis “multicollinearity” refers to _________. A) two or more predictors sharing the same linear relationship with the outcome variable B) a high degree of correlation between the dependent variables C) the equality of the variance of the dependent throughout its range of values D) None of the above. 4. In multiple regression analysis, which of the following is an example of a subset selection algorithm? A) Forward selection B) Backwards elimination C) Stepwise regression D) All of the above 5. _________ is an important property of a good model. A) Complexity B) Independence C) Parsimony D) None of the bove 6. An assumption that applies to the linear multiple regression method is that the distribution of the error term values should be ________. A) standardized ...

Words: 460 - Pages: 2

Premium Essay

Linear Regression

...Introduction Simple linear regression is a model with a single regressor x that has a relationship with a response y that is a straight line. This simple linear regression model is y = β0 + β1x + ε where the intercept β0 and the slope β1 are unknown constants and ε is a random error component. Testing Significance of Regression: H0: β1 = 0, H1 : β1 ≠ 0 The hypotheses relate to the significance of regression. Failing to reject H0: β1 = 0 implies that there is no linear relationship between x and y. On the other hand, if H0: β1 = 0 is rejected, it implies that x is of value in explaining the variability in y. The following equation is the Fundamental analysis-of-variance identity for a regression model. SST = SSR + SSRes Analysis of variance (ANOVA) is a collection of statistical models used in order to analyze the differences between group means and their associated procedures (such as "variation" among and between groups), developed by R. A. Fisher. In the ANOVA setting, the observed variance in a particular variable is partitioned into components attributable to different sources of variation.  P value or calculated probability is the estimated probability of rejecting the null hypothesis (H0) of a study question when that hypothesis is true. VIF (the variance inflation factor) for each term in the model measures the combined effect of the dependences among the regressors on the variance of the term. Practical experience indicates that if any of...

Words: 483 - Pages: 2

Premium Essay

Linear Regression

...Chapter 4 Multiple Linear Regression Section 4.1 The Model and Assumptions Objectives Participants will:  understand the elements of the model  understand the major assumptions of doing a regression analysis  learn how to verify the assumptions  understand a median split 3 The Model y   o  1x1  ...   p x p   or in Matrix Notation Dependent Variable nx1 Unknown Parameters (p+1) x 1 Y  X e Independent Variables – n x(p+1) Error – nx1 4 Questions How many unknown parameters are there? Can you name them? How many populations will be sampled? What are conceptual populations? 5 Major Requirements for Doing a Regression Analysis The errors are normally distributed (not Y). Constant variance – What is the null hypothesis? Linear in the parameters Errors are independent. Some people call these assumptions. EY   () X 6 Example We have observed y = response (change in blood pressure) and x = dosage level of a drug. We assume a linear relationship between E(y) and x. The two graphs are the same, but they have been rotated to give additional views. 7 continued... Example 8 continued... Example      Sketch E(y). Based on the graphs, make comments about the assumptions. Do they appear to be satisfied or violated? How many populations are represented by the graphs? List all of the parameters. Write the model down. 9 Checking Assumptions Testing the residuals for normality PROC CAPABILITY ...

Words: 1277 - Pages: 6

Premium Essay

Forecasting Gold Prices Using Multiple Linear Regression Method

...Forecasting Gold Prices Using Multiple Linear Regression Method Z. Ismail, 2A. Yahya and 1A. Shabri Department of Mathematics, Faculty of Science 2 Department of Basic Education, Faculty of Education University Technology Malaysia, 81310 Skudai, Johor Malaysia 1 1 Abstract: Problem statement: Forecasting is a function in management to assist decision making. It is also described as the process of estimation in unknown future situations. In a more general term it is commonly known as prediction which refers to estimation of time series or longitudinal type data. Gold is a precious yellow commodity once used as money. It was made illegal in USA 41 years ago, but is now once again accepted as a potential currency. The demand for this commodity is on the rise. Approach: Objective of this study was to develop a forecasting model for predicting gold prices based on economic factors such as inflation, currency price movements and others. Following the melt-down of US dollars, investors are putting their money into gold because gold plays an important role as a stabilizing influence for investment portfolios. Due to the increase in demand for gold in Malaysian and other parts of the world, it is necessary to develop a model that reflects the structure and pattern of gold market and forecast movement of gold price. The most appropriate approach to the understanding of gold prices is the Multiple Linear Regression (MLR) model. MLR is a study on the relationship between a single dependent...

Words: 3920 - Pages: 16

Free Essay

Psych 625 Week 5 Learning Team Assignment Linear Regression

...PSYCH 625 Week 5 Learning Team Assignment Linear regression To Buy this Class Copy & paste below link in your Brower http://www.homeworkregency.com/downloads/psych-625-week-5-learning-team-assignment-linear-regression/ Or Visit Our Website Visit : http://www.homeworkregency.com Email Us : homeworkregency@gmail.com PSYCH 625 Week 5 Learning Team Assignment Linear regression PSYCH 625 Week 5 Learning Team Assignment Linear regression To Buy this Class Copy & paste below link in your Brower http://www.homeworkregency.com/downloads/psych-625-week-5-learning-team-assignment-linear-regression/ Or Visit Our Website Visit : http://www.homeworkregency.com Email Us : homeworkregency@gmail.com PSYCH 625 Week 5 Learning Team Assignment Linear regression PSYCH 625 Week 5 Learning Team Assignment Linear regression To Buy this Class Copy & paste below link in your Brower http://www.homeworkregency.com/downloads/psych-625-week-5-learning-team-assignment-linear-regression/ Or Visit Our Website Visit : http://www.homeworkregency.com Email Us : homeworkregency@gmail.com PSYCH 625 Week 5 Learning Team Assignment Linear regression PSYCH 625 Week 5 Learning Team Assignment Linear regression To Buy this Class Copy & paste below link in your Brower http://www.homeworkregency.com/downloads/psych-625-week-5-learning-team-assignment-linear-regression/ Or Visit Our Website Visit : http://www.homeworkregency.com Email Us : homeworkregency@gmail.com PSYCH...

Words: 2736 - Pages: 11

Premium Essay

Statistics and Spss

...ANOVA table. | | | | | | |3.131a |2 |.209 | | |3.433 |2 |.180 | | |.543 |1 |.461 | | |40 | | | Figure 6.1 Cross table of satisfaction and sex at α=0.05 The p-value, which is 0.209, is very obviously greater than our chosen level of significance, 0.05. The null hypothesis is accordingly not rejected, i.e. the level of satisfaction is independent of the sexes. 7. Correlation and regression The MBA programme leader has become so enthralled with the benefits of using statistical analysis as a performance indicator toolkit, then decides that further analyses on student performance, expected and anticipated salaries ought to be carried out. a. Produce a...

Words: 659 - Pages: 3

Premium Essay

Does Exchange Rate Exposure Matter?

...Does Exchange Rate Exposure Matter? By Craig Doidge, John Griffin, and Rohan Williamson* Draft: May 8, 2002. Comments Welcome. _________________ Doidge is at the Ohio State University, Fisher College of Business, Columbus, OH 43210, email: doidge.4@osu.edu. Griffin is at Arizona State University, College of Business, Tempe, AZ 85287, email: john.griffin@asu.edu, and Williamson is at Georgetown University, McDonough School of Business, Washington, DC 20057, email: williarg@georgetown.edu. This paper replaces an earlier draft entitled, “An International Comparison of Exchange Rate Exposure.” We thank Yiorgos Allayannis, James Linck, Patrick Kelly, Spencer Martin, Felix Meschke, Clifford Smith, René Stulz, and participants at the International Finance Conference at the Georgia Institute of Technology, Cornell University, Georgetown University, and the Ohio State University for helpful comments and suggestions. We also thank Selim Topaloglu for research assistance. Williamson acknowledges research support from the Capital Markets Research center at Georgetown University. All errors are the responsibility of the authors. * Does Exchange Rate Exposure Matter? Abstract Previous literature finds mixed empirical support for a relation between exchange rate exposure and its theoretical determinants and that exposure is of negligible economic importance. To re-examine the nature and the economic significance of the exchange rate to firm value relation, we construct an international...

Words: 16281 - Pages: 66

Premium Essay

Jjklj

...Correlation Correlation is a statistical technique that can show whether and how strongly pairs of variables are related. For example, height and weight are related; taller people tend to be heavier than shorter people. The relationship isn't perfect. People of the same height vary in weight, and you can easily think of two people you know where the shorter one is heavier than the taller one. Nonetheless, the average weight of people 5'5'' is less than the average weight of people 5'6'', and their average weight is less than that of people 5'7'', etc. Correlation can tell you just how much of the variation in peoples' weights is related to their heights. Although this correlation is fairly obvious your data may contain unsuspected correlations. You may also suspect there are correlations, but don't know which are the strongest. An intelligent correlation analysis can lead to a greater understanding of your data. Techniques in Determining Correlation There are several different correlation techniques. The Survey System's optional Statistics Module includes the most common type, called the Pearson or product-moment correlation. The module also includes a variation on this type called partial correlation. The latter is useful when you want to look at the relationship between two variables while removing the effect of one or two other variables. Like all statistical techniques, correlation is only appropriate for certain kinds of data. Correlation works for quantifiable data...

Words: 2286 - Pages: 10

Premium Essay

Marketing Research

...FITNESS LEVEL AT IFMR [Document subtitle]   Contents PROBLEM STATEMENT 2 Research Objective 2 INTRODUCTION 2 Variable View in SPSS 3 Data View in SPSS 3 DESCRIPTIVE STATISTICS 4 Gender Statistics 4 BMI Health Statistics 4 Factors Influencing Exercise Participation 7 Factors Influencing Exercise Non- Participation 8 CONFIDENCE INTERVAL 9 CROSS-TABULATIONS WITH CHI-SQUARE ANALYSIS: 10 T-Test Analysis: 14 One-Sample T-Test: 14 Independent Sample T-Test: 16 Paired Sample T-Test: 17 FACTOR ANALYSIS 20 KMO measure of sampling adequacy 21 Bartlett’s test of sphericity 21 LINEAR MULTIPLE REGRESSION 21 Multiple Linear Regression Equation: 25 ONE-WAY ANOVA TEST 26 INTERPRETATION OF ATTITUDE SCALE 29 CONCLUSION 31   PROBLEM STATEMENT In what ways can IFMR improve the fitness level among its population by better analyzing factors influencing exercise participation & exercise non-participation. Research Objective The research attempts to analyze the fitness level of students in the IFMR, as well as ways to improve the fitness level and what exercise they do on regular basis to maintain their physical health. Moreover, a research objective is to collect statistical information of the students and the factors influencing exercise participation & non-participation. The data that was received from the questionnaires and the responses were further analyzed through statistical analysis with the help of SPSS. INTRODUCTION The report details the analysis made...

Words: 1512 - Pages: 7

Premium Essay

Multicultural Buyer/Supplier Relationship: the Impact of Importance of Trust and Ease of Adaptation on Continuity.

...Multicultural buyer/supplier relationship: the impact of importance of trust and ease of adaptation on continuity. Multicultural buyer/supplier relationship: the impact of importance of trust and ease of adaptation on continuity. Summary Abstract: 2 Introduction: 2 I) Theory: 3 Research question 3 II) Literature review: 3 Buyer-supplier relationship 3 Importance of trust 3 Adaptation 3 Continuity 4 Culture and buyer-supplier relationship 4 III) Hypothesis and conceptual framework 5 IV) Methodology 7 Research Design 7 Data Collection 7 Reliability and Validity analysis 8 Model significance and assumptions 9 V) Results 13 Hypothesis validation 15 VI) Limitations and further research: 16 Conclusions and managerial implications 18 Appendix 19 Survey: 19 References: 20 Multicultural buyer/supplier relationship: the impact of importance of trust and ease of adaptation on continuity. Abstract In today’s globalized world, more and more companies are dealing with international partners or tends to integrate international territories in order to expand their business. Those companies have, thus, a strong need to understand the impact of cultural differences on the working relationships between key dyads in the business process. The purpose of this study is to investigate the effects of cultural differences on specific factors (Importance of trust, Ease of adaptation and continuity) that determine the efficiency...

Words: 6837 - Pages: 28

Premium Essay

Module 3 Assignment

...1. Report the sample you selected and the question that was explored in the study. * There is a correlation between x and y. The scatter chart shows that the more hours a student studies the higher their grade percentage will be. 2. Report the r2 linear correlation coefficient and the linear regression equation produced in the Excel spreadsheet. * The linear correlation coefficient is positive. * The r^2 linear correlation coefficient is 0.785 * The linear regression equation is y=1.5608x+55.767 3. What would be the value of Pearson’s r (simply the square root of r2)? * R^2 is 0.785, which means that 78.5% of the total variation in y can be explained by the relationship between x and y.  The other 21.5% remains unexplained.   4. Would Pearson’s r be positive or negative? What does this imply about the relationship between the factors in this study? * Pearson’s r is positive and equal to 1.0. Since Pearson r is positive this implies that there is a strong correlation between x and y. 5. What is the implication of any correlation found between the variables in the study you picked? * X & Y have a strong positive correlation. It seems the more hours put into studying the better the grade percentages will be. 6. Does this correlation imply a causal relationship? Explain. * There is a casual relationship, because on the graph it shows positive correlation, because the slopes are increasing. That implies if you spend more...

Words: 301 - Pages: 2

Free Essay

Vfvv

...Journal of Mechanical Engineering and Automation 2015, 5(1): 20-28 DOI: 10.5923/j.jmea.20150501.03 Effect of Evaporator Heater Power Input and Refrigerant Flow Rate on the Performance of a Refrigerator – Developing Empirical Models Ali Naif*, Abdulkareem Shafiq Mahdi Al-Obaidi, Mohammad H. Nassir School of Engineering, Taylor’s University, Malaysia Abstract Refrigerators normally are systems that are used to preserve perishable goods in a house hold by reducing the temperature of the food compartments. However, refrigerators are also infamous for their high electricity consumptions. This paper presents first a comparison between theoretical and experimental determination of the tons of refrigeration (TR) of a vapor compression refrigeration cycle (VCRC). Then, it was looked into the derivation of empirical models, grounded on experimental results, which would provide refrigerator designers a reliable mean to check on the impact of each examined parameter on the TR during the preliminary stage of refrigerator design. It was noted that both evaporator heater power input (EHPI) and refrigerant flow rate (RFR) positively affected the tons of refrigeration, while the effects of condenser water flow rate (CWFR) was negligible. A total of three models generated. As the accuracy of the data for all models were about 99.7%, the minute difference had to be looked in to. Hence, Model 1, considering both evaporator heater power input (EHPI) and refrigerant flow rate (RFR)...

Words: 5785 - Pages: 24

Premium Essay

Math

...1. Report the sample you selected and the question that was explored in the study. * There is a correlation between x and y. The scatter chart shows that the more hours a student studies the higher their grade percentage will be. 2. Report the r2 linear correlation coefficient and the linear regression equation produced in the Excel spreadsheet. * The linear correlation coefficient is positive. * The r^2 linear correlation coefficient is 0.785 * The linear regression equation is y=1.5608x+55.767 3. What would be the value of Pearson’s r (simply the square root of r2)? * R^2 is 0.785, which means that 78.5% of the total variation in y can be explained by the relationship between x and y. The other 21.5% remains unexplained. 4. Would Pearson’s r be positive or negative? What does this imply about the relationship between the factors in this study? * Pearson’s r is positive and equal to 1.0. Since Pearson r is positive this implies that there is a strong correlation between x and y. 5. What is the implication of any correlation found between the variables in the study you picked? * X & Y have a strong positive correlation. It seems the more hours put into studying the better the grade percentages will be. 6. Does this correlation imply a causal relationship? Explain. * There is a casual relationship, because on the graph it shows positive correlation, because the slopes are increasing. That implies if you spend more time studying your...

Words: 300 - Pages: 2