Stata manual iv regression

Stata manual iv regression. Remarks and examples stata. spshape2dta did its magic and created two Stata datasets for us. 10 Preﬁx commands. ivregress fits linear models where one or more of the regressors are endogenously determined. com poivregress performs partialing-out lasso instrumental-variables linear regression. repair omitted and 10 obs not used. Learn how to fit instrumental-variables models for endogenous covariates in Stata using the *ivregress* command. ivregress supports estimation via two-stage least squares (2SLS), limited-information maximum likelihood (LIML), and generalized method of moments (GMM). Highlights. With its complex mechanics In Act IV, Scene I, Juliet arrives crying at Friar Lawrence’s, where she finds Paris, who believes she is crying over Tybalt’s death. . One of the first Stata is a powerful data analysis software widely used by researchers, economists, and statisticians for its comprehensive range of features. 1/SE. One of the strengths of Stata lies In the field of statistics, log binomial mixed effects models are powerful tools for analyzing complex data sets. com and AutoZone. Stata will generate a single piece of output for a multiple regression analysis based on the selections made above, assuming that the eight assumptions required for multiple regression have been met. Stata is a user-friendly statistical software that enables rese When it comes to downloading software, understanding the system requirements is crucial. Both the KVO and the TKO rates r Appliance manuals are notorious for getting misplaced or lost just when you need them. 230498 fd requests the ﬁrst-differenced regression estimator. 2023. One of the strengths of Stata is its a Stata is a powerful statistical software package that is widely used in various fields, including economics, social sciences, and public health. Robust penalized quantile regression estimation for panel data. College Station, TX: Stata Press. eprobit— Extended probit regression 5 indepvars, varlisten, varlisttr, and varlists may contain factor variables; see [U] 11. Stata, a widely used statistical software package, offers a compre The number “IV” is the Roman numeral of the number four. Journal of Multivariate Analysis, 91(1):74{89, October 2004. Books Datasets Authors Instructors What's new Accessibility [MI] Stata Multiple-Imputation Reference Manual [MV] Stata Multivariate Statistics Reference Manual [PSS] Stata Power and Sample-Size Reference Manual [P] Stata Programming Reference Manual [SEM] Stata Structural Equation Modeling Reference Manual [SVY] Stata Survey Data Reference Manual [ST] Stata Survival Analysis and Epidemiological Tables arima— ARIMA, ARMAX, and other dynamic regression models 3. exponential conditional mean model) in which one or more of the regressors are endogenous. When you’re attempting to repair your craftsman product and don’t have a manual, it can be incredibly frustrating. com Remarks are presented under the following headings: Median regression Quantile regression Estimated standard errors Interquantile and simultaneous-quantile regression What are the parameters? Median regression qreg ﬁts quantile regression models. Except, when you bought them, you didn’t think you’d need the user ma Free printable first aid manuals are available on the Red Cross website or the Triple One Care website. It provides additional features, such as testing for endogeneity, weak instruments, and overidentification. arima y, arima(2,1,3) The latter is easier to write for simple ARMAX and ARIMA models, but if gaps in the AR or MA lags are to be modeled, or if different operators are to be applied to independent variables, the ﬁrst syntax is required. Hearts of Iron IV is a grand strategy game that takes players back to the turbulent era of World War II. The company makes it easy to get support for your products, including requesting Elect Mettler Toledo manufactures scales and analytics instruments. This command estimates coefﬁcients, standard errors, and conﬁdence intervals and performs tests for variables of interest, both exogenous and endogenous, while using lassos to select from among potential control Nov 16, 2022 · ivpoisson fits a Poisson regression model (a. Stata’s ivregress command suppresses the printing of an R 2 on 2SLS/IV if the R 2 is negative, which is to say, if the model sum of squares is negative. Danuso, F. You can also get a service manual for your CAT The DSM-IV lists nine major diagnostic criteria to diagnose patients with emotionally unstable personality disorder, also known as borderline personality disorder, according to BPD The KVO rate, in health management, is an acronym for keep veins open. Whether you are a student, researcher, or professional, having access to this powerful tool can greatly Stata is a powerful statistical software package widely used by researchers and analysts across various disciplines. Poisson is frequently used to model count outcomes or to model nonnegative outcome variables. Read on for 10 ways to u Sn(SO3)2 is the molecular formula for the chemical compound tin(IV) sulfite. com ena A Caterpillar service manual is different than a CAT owner’s manual, although you can get both types of manuals from the CAT website. The weak IV test is just the F-value for testing both coefﬁcients of z 1 and z 2 being zero. Performance in small samples may be poor. Here are a number of ways to get the manual Are you a proud owner of a Vizio TV or other Vizio product? If so, you might find yourself in need of an owners manual at some point. regress— Linear regression 5 SeeHamilton(2013, chap. xtreg with the re option ﬁts random PDF-1. Apr 22, 2024 · ivregress: ivregress is a built-in command provided by Stata for instrumental variables regression. 25) Menu qreg Statistics >Nonparametric analysis >Quantile regression iqreg Statistics >Nonparametric analysis >Interquantile regression sqreg Statistics >Nonparametric analysis >Simultaneous-quantile Remarks and examples stata. You must have the same levels of factor variables in all equations that have factor variables. Journal When reading this manual, you will ﬁnd references to other Stata manuals, for example, [ U ] 27 Overview of Stata estimation commands ;[ R ] regress ; and[ D ] reshape . com. Nov 16, 2022 · Estimating lasso for bweight using plugin output omitted Cross-fit partialing-out Number of obs = 4,642 IV linear model Number of controls = 104 Number of instruments = 42 Number of selected controls = 27 Number of selected instruments = 5 Number of folds in cross-fit = 10 Number of resamples = 1 Wald chi2(4) = 97. pdf) /S /GoToR /D (igigInstallationGuide) >> endobj 6 iv) if in weight, reg err optoptions Control-function estimator ivpoisson cfunction depvar varlist 1 (varlist 2 = varlist iv) if in weight, options reg err opt Description Model additive add regression errors to the conditional mean term; the default multiplicative multiply regression errors by the conditional mean term 1 IV Regression with One Regressor and One Instrument Y i = β 0 + β 1X i + u i • IV regression breaks X into two parts: a part that might be correlated with u, and a part that is not. The Stata Blog: Estimating parameters by ML and method of moments using mlexp and gmm; The Stata Blog: Understanding the generalized method of moments: A simple example; The Stata Blog: Testing model specification and using the program version of gmm; See tests, predictions, and effects. Nov 16, 2022 · Is there a way I can do it in Stata? I can regress W on Q and get the predicted W, and then use it in the second-stage regression. SE Introduction Model and estimator Asymptotics Traditional Panel Grouped Stata commands Application Grouped IV Quantile Regression Chetverikov et al. arima D. However, even the best appliances can encounter issues from Electrolux manufactures a wide array of home products for the kitchen, laundry and elsewhere. Nov 16, 2022 · StataCorp. Because the conditional mean modeled by interval regression is linear, the coefﬁcients are interpreted the same way they are in ordinary least-squares regression; see[R] regress. Stata Press 4905 Lakeway Drive College Station, TX 77845, USA 979. Standard regression: y = xb +u no association between x and u; OLS consistent x y u Christopher F Baum (Boston College, DIW) IV techniques in economics and ﬁnance DESUG, Berlin, June 2008 4 / 49 sureg— Zellner’s seemingly unrelated regression 3 varlist1,:::, varlistN may contain factor variables; see [U] 11. com The basic idea of Poisson regression was outlined byColeman(1964, 378–379). I have a data set of roughly 900 obs and am trying to perform a regression on 17 variables (no panel data) plus their respective interaction terms with one variable. Instrumental Variables Estimation in Stata Introduction Why not always use IV? It may be difﬁcult to ﬁnd variables that can serve as valid instruments. k. 1. Thus if your dependent variable takes on the values 0 and estat firststage report “ﬁrst-stage” regression statistics estat overid perform tests of overidentifying restrictions These commands are not appropriate after the svy preﬁx. repair != 0 predicts failure perfectly; 1. Example 2: Tobit model for a corner solution Click on the button. 2clogit— Conditional (ﬁxed-effects) logistic regression Menu Statistics >Categorical outcomes >Conditional logistic regression Description clogit ﬁts what biostatisticians and epidemiologists call conditional logistic regression for matched case–control groups (see, for example,Hosmer, Lemeshow, and Sturdivant[2013, chap. Nov 16, 2022 · We find that a 1% increase of older cars per capita increases pollution by 0. If you need to know how to use your Dometic appliance, you can find Dometic m You can download and view free auto repair manuals from sites such as ManualsLib. varlist 2 is the list of endogenous variables. 20 Prob > chi2 = 0. • This is done using an instrumental variable, Z i, which is IV in STATA IV regression of Y on X using instrument Z: ivregress 2sls y (x = z), robust IV regression of Y on X using instrument Z and controls W 1 and W 2: ivregress 2sls y w1 w2 (x = z), robust IV regression of Y on X using instruments Z 1 and Z 2 and controls W 1 and W 2: ivregress 2sls y w1 w2 (x = z1 z2), robust where 2sls stands for Two iv) if in weight, mle options Two-step estimator ivprobit depvar varlist 1 (varlist 2 = varlist iv) if in weight, twostep tse options varlist 1 is the list of exogenous variables. The ﬁtted value of ﬁrst-stage regression A quantile regression approach for estimating panel data models using instrumental variables. When it comes to manuals for various products and appliances, having access to fre The difference between manual and automatic cars is that manual cars use manual transmission whereas automatic cars use automatic transmission. fe requests the ﬁxed-effects (within) regression estimator. Stage IV is the most severe form of this br The Dometic company has been in business since 1968, when it started as Electrolux Leisure Appliances. 4600 [email protected] Links. dta. Title stata. 1, pp. (4) are tested because no particular variables are specified in this STATA command. mle options Description 4churdle— Cragg hurdle regression The following option is available with churdle but is not shown in the dialog box: coeflegend; see[R] Estimation options. Fortunately, it isn’t impossible to find repair manuals when you Are you a proud owner of a serger machine but find yourself in need of its manual? Look no further. One area that has seen significant advancements in recent years is intravenou Hearts of Iron IV is a popular strategy video game that allows players to take control of any nation during World War II. ivregress supports estimation via two-stage least squares (2SLS), Instrumental Variables Regression Evaluating IV Assumptions More general Stata commands Basics of IV/2SLS Performing IV regression using the -ivreg2- package ctd 2SLS Regression in Stata. varlist iv is the list of exogenous variables used with varlist 1 as instruments for varlist 2. The precision of IV estimates is lower than that of OLS estimates (least squares is just that). Most variables that have an effect on included endogenous variables also have a direct effect on the dependent variable. The short answer. 058, and a 1% increase in industrial production increases pollution by 0. If . 035. 696. In reality, Juliet is crying because Romeo, he As of 2015, an authentic Currier and Ives lithograph that is not a reproduction may sell for $100-300, according to Christopher Lane, an antiques shop owner who consults for PBS’ “ The molecular formula for tin (IV) phosphate is Sn3(PO4)4. With its immersive gameplay and attention to detail, many According to the University of Connecticut, the criterion variable is the dependent variable, or Y hat, in a regression analysis. The precision of IV estimates is likely to be lower than that of OLS We demonstrate the uses of Stata for IV regression problems. The first part reports two bandwidths, one for calculating the mean and the other for calculating the effect. com Remarks are presented under the following headings: Introduction to complementary log-log regression Robust standard errors Introduction to complementary log-log regression cloglog ﬁts maximum likelihood models with dichotomous dependent variables coded as 0/1 (or, To say a person has “regressive tendencies” is a way of saying that the individual being discussed has a tendency to behave in a less mature, or even childish, manner when he or sh Stata software is widely used in the field of statistics and data analysis. See [U] 27 Overview of Stata estimation commands for a list of other regression commands that may be of interest. Quick start. There are also two typ In today’s digital age, finding information at our fingertips has become increasingly convenient. According to the Royal Society of Chemistry, tin (IV) phosphate is an ionic compound with a molar mass of 736. By isolating the part that is not correlated with u, it is possible to estimate β 1. They are only interested inγ(τ). It combines a selection model that determines The option first reports the ﬁrst-stage regression that regresses x1 onto z1; z2 and x 2: The residual of the ﬁrst-stage regression is the bad part of apple, and can be used to implement Hausman test. repair note: 1. There are two parts to the output. (7) estat endogenous. In a manual car, the driver is respo The chemical name of Sn3(PO4)4 is tin(IV) phosphate, according to Quia. This will generate the output. sg1: Nonlinear regression command. a. (2016) consider a grouped (IV) quantile regression model, which fits into our setup. 0000 Bootstrapped quantile regression Single quantile regression for the 25th quantile with bootstrap standard errors bsqreg y x1 x2 i. spivregress: spatial IV regression. com, JustGiveMeTheDamnManual. In this article, we will guide you through the ultimate resource for free serger Whirlpool appliances are renowned for their efficiency, durability, and performance. DescriptionQuick startMenuSyntax OptionsRemarks and examplesStored resultsMethods and formulas AcknowledgmentsReferencesAlso see Description xtreg ﬁts linear regression models for panel data. These effects along with the remaining Note: Effect estimates are averages of derivatives. UsingDiﬀerentBaseCategories • Bydefault,thesmallest-valuedcategoryisthebasecategory • Thiscanbeoverriddenwithincommands b#. If the variable is constant across each alternative (a case-speciﬁc variable), the regression coefﬁcient associated with the base alternative is not identiﬁable. You put the user manuals in a safe place, right? If you can’t remember where you placed them after a couple of yea Whether you’re searching for free manuals for motorcycles online or you’re willing to pay to get the information you need, there are a few ways to find them. They suggest a different two-stages estimator: 1 For each i and quantile τ regress performs linear regression, including ordinary least squares and weighted least squares. For example, participation in a study-skills program increases the expected uncensored GPA by 0. 992087 Iteration 1: Log likelihood = -22. The Roman numeral for 4 is IV, 5 is V, 6 is VI, 7 is VII and 8 is VIII. spivregress fits the model like the following: spivregress y1 x1 x2 (y2 y3 = z1 z2 z3), dvarlag(W) errorlag(M) ivarlag(W: x1) y2 and y3 are endogenous variables, and z1, z2, and z3 are instruments. First, let’s open up the data in Stata noting that we are using a “Cross-sectioned” version of Tobias and Koop that focuses on 1983. 1 Video example PDF documentation in Stata 1. regress speciﬁes that all the covariates are to be treated as exogenous and that the instrument list is to be ignored. ivreg2: As a user-created command, ivreg2 extends the functionality of ivregress. 2 Example datasets Various examples in this manual use what is referred to as the automobile dataset, auto. The following postestimation commands are also available: Command Description contrast contrasts and ANOVA-style joint tests of estimates Nov 16, 2022 · The discussion below focuses on 2SLS/IV; the issues for 3SLS are the same. 483187 Iteration 2: Log likelihood = -22. Example 42g— One- and two-level mediation models (multilevel) 5 which is most easily revealed by typing. 4. Quantile instrumental&dash;variables (IV) estimators. For example, residing in a rural area lowers the expected income by $3,043 and each additional year of schooling raises the expected income by $1,335. 56 points. 4 %性咆 1 0 obj /F (stoc. com, Free-Auto-Repair-Manuals. For each variable speciﬁed in the variable list, there will be one regression coefﬁcient for each alternative of that level of the hierarchy. Cameron Stata interprets a value of 0 as a negative outcome (failure) and treats all other values (except missing) as positive outcomes (successes). In Stata, after running regression type: predict e, resid [U] 1 Read this—it will help5 1. In the presence of weak instruments (excluded Bivariate probit regression of y1 and y2 on x1 biprobit y1 y2 x1 Bivariate probit regression of y1 and y2 on x1, x2, and x3 biprobit y1 y2 x1 x2 x3 Constrain the coefﬁcients for x1 to equality in both equations constraint define 1 _b[y1:x1] = _b[y2:x1] biprobit y1 y2 x1 x2 x3, constraints(1) Seemingly unrelated bivariate probit regression Jan 23, 2020 · Dear all, Greetings to all contributors from someone new to the forum and a user of Stata 15. With their advanced features and capabilities, they allow us to stay connected, access in Hospitals use an intravenous sodium chloride solution to supply water and salt to the body to alleviate dehydration, according to Healthline. Inverse quantile regression (IQR) Smoothed estimating equations estat firststage report “ﬁrst-stage” regression statistics estat overid perform tests of overidentifying restrictions +estat weakrobust perform inference robust to weak instruments estat sbknown perform tests for a structural break with a known break date estat single perform tests for a structural break with an unknown break date Aug 14, 2024 · Another assumption of the regression model (OLS) that impact the validity of all tests (p, t, and F) is that residuals behave ‘normal’. Thus, we can interpret the coefﬁcients just as we would the coefﬁcients from OLS. cloglog— Complementary log-log regression 3 Remarks and examples stata. In this article, we will make use of the WAGE2. Thus, most of the justiﬁcation for the use of IV is asymptotic. Statistics >Endogenous covariates >Single-equation instrumental-variables regression Description ivregress ﬁts a linear regression of depvar on varlist 1 and varlist 2, using varlist iv (along with varlist 1) as instruments for varlist 2. poisson— Poisson regression 3 Remarks and examples stata. gsem, coeflegend (output omitted) Thus we can obtain the indirect effect by typing Remarks and examples stata. Or use the ivregress 2sls command to run the entire model. 96 that level. The Roman numeral for 9 is IX, and the Roman numeral for A Caterpillar service manual is different than a CAT owner’s manual, although you can get both types of manuals from the CAT website. We can run a 2SLS regression in two ways: running the first-stage, obtaining x_hat, and using it to run the second stage. Contact us. com xtreg — Linear models for panel data+ +This command includes features that are part ofStataNow. Stata Interpreting and Reporting the Stata Output of Multiple Regression Analysis. 17) andJohnson, Kemp, and Kotz(2005, chap. Reprinted in Stata Technical Bulletin Reprints, vol. With its intricate mechanics and vast scope, mastering the game can be chal Unfortunately, the prognosis of a Stage IV pancreatic patient is bleak, with only a 1 percent survival rate five years after diagnosis, according to the American Cancer Society. If As the field of healthcare continues to evolve, so does the need for skilled and knowledgeable nurses. The compound contains one atom of tin, represented by the symbol Sn; six atoms of oxygen, shown by the When it comes to household appliances, having a reliable and efficient brand like Whirlpool can make all the difference. bootstrap, by, collect, jackknife, and statsby are allowed; see [U] 11. 3 Factor variables. com probit — Probit regression DescriptionQuick startMenuSyntax OptionsRemarks and examplesStored resultsMethods and formulas ReferencesAlso see Description probit ﬁts a probit model for a binary dependent variable, assuming that the probability of a 8qreg— Quantile regression Remarks and examples stata. This is especially true for complex statistical analysis tools like Stata. One molecule of lead(IV) nitrite contains one atom of lead, represented by Hearts of Iron IV is a grand strategy game set in World War II that allows players to take control of any nation during the war and guide it to victory. 3) for an introduction to linear regression using Stata. ManualsLib. We can use ordinary least squares (OLS) regression to consistently estimate a model of the following sort. 7]) and what Title stata. I am trying to replicate the ivreg output of a regression performing manually the first stage, predicting the instrument after the first stage and running the second stage regression w 4mediate— Causal mediation analysis omvarlist and mmvarlist may contain factor variables; see [U] 11. Step 2: Prepare the data for analysis Stata Press, a division of StataCorp LLC, publishes books, manuals, and journals about Stata and general statistics topics for professional researchers of all disciplines. Roger Koenker. In today’s fast-paced world, smartphones have become an essential part of our daily lives. The first place to check for free Vizio owners Glioblastoma, which is a type of cancerous brain tumor, is actually stage IV astrocytoma, according to the National Brain Tumor Society. com churdle ﬁts a linear or an exponential hurdle model. dta spshape2dta also linked the two files. But to truly get the most out of your Whirlpool appliance, it’s important to have a thorough un We’ve all been there—you moved to a new home or apartment, and it’s time to set up electronics and components. See New in Stata 18 to learn about what was added in case, a regression model is ﬁt of the original outcome on covariates that vary within levels of the groupvars and timevar interaction. Lead(IV) nitrite is also known as plumbic nitrite. com Remarks are presented under the following headings: Overview Basic examples Average treatment effect (ATE) Average treatment effect on the treated (ATET) Overview etregress estimates an ATE and the other parameters of a linear regression model that also includes an endogenous binary-treatment variable. For a general discussion of linear regression, seeKutner et al. spivregress is very similar to spregress, but it allows endogenous covariates (instrumental variables regression). regress speciﬁes that all the covariates be treated as exogenous and that the instrument list be ignored. dta The other is a Stata dataset containing the other data that were in the shapefile bundle: tl_2016_us_county. The ﬁrst ex- IV estimators are innately biased, and their ﬁnite-sample properties are often problematic. Residuals (here indicated by the letter “e”) are the difference between the observed values (Y) and the predicted values (Yhat): e = Y –Yhat. Saline drips are mostly water with sma The adjusted r-square is a standardized indicator of r-square, adjusting for the number of predictor variables. (2005). All the endogenous variables in Eq. Load data and summarize: by IV methods. One molecule of lead(IV) nitrite contains one atom of lead, represented by A compounded IV admixture is a solution of sterile substances prepared by a certified pharmacy technician for the purpose of administration to a patient through an intravenous rout The chemical formula for lead(IV) nitrite is Pb(NO2)4. Carlos Lamarche. Specifying regress causes xtivreg to ﬁt the requested panel-data regression model of depvar on varlist 1 and varlist 2, ignoring varlist iv. The standard errors will, however, be incorrect. y, ar(1/2) ma(1/3) is equivalent to. Stata 18 Survival Analysis Reference Manual. With its immersive gameplay and attention to detail, many The molecular formula for tin (IV) phosphate is Sn3(PO4)4. One is a Stata-format shapefile: tl_2016_us_county_shp. The company is one of the largest providers of instruments used in laboratory, food retail and industrial markets. This STATA command generates Durbin and Wu-Hausman tests (the tobit— Tobit regression 5 tobit reports the coefﬁcients for the latent regression model. 4) for information I use Stata. The estimates of the group-time level effects from this regression are used to construct a new dependent variable. The criterion variable is the variable that the an Hearts of Iron IV is a popular strategy video game that allows players to take control of any nation during World War II. This compound is a chemical combination of the following elements: tin, oxygen and phosphorous. Missing R 2 s, negative R 2 s, and negative model sum of squares are all the same issue. Dohoo, Martin, and Stryhn(2012,2010) discuss linear regression using examples from epidemiology, and Stata datasets and do-ﬁles used in the text are available. Iteration 0: Log likelihood = -26. 0154 g/mol. In the Roman number notation system, “I” is the equivalent of the number one in the Hindu-Arabic numbering system, and “V” The chemical formula for lead(IV) nitrite is Pb(NO2)4. 1991. The Triple One Care website offers a simple first aid manual, and the Red Cr Whether you’re using a manual lift truck or a lithium-ion solution, product-heavy businesses rely on material handling equipment for safety and efficiency. speciﬁesthevalue#asthebase logit— Logistic regression, reporting coefﬁcients 7 Let’s try Stata on this problem. 7) andCameron and Trivedi(2010, chap. Instrumental variable regressions are used when one wants to establish a causal channel through which the explanatory variable affects the dependent variable, but one is worried that the error term in the OLS regression is correlated with the explanatory variable. Stata Technical Bulletin 1: 17–19. If you have a KitchenAid product, you’re in luck. iv) if in weight, reg err optoptions Control-function estimator ivpoisson cfunction depvar varlist 1 (varlist 2 = varlist iv) if in weight, options reg err opt Description Model additive add regression errors to the conditional mean term; the default multiplicative multiply regression errors by the conditional mean term Jul 1, 2021 · The following STATA command can be used immediately after implementing the IV regression (ivregress) to check for possible endogeneity issues. a, quantile(. depvar, indepvars, depvarsen, varlisten, depvartr, varlisttr, tvar, depvars, and varlists may contain time-series Nov 16, 2022 · References. Economics Letters, 104(3):133 { 135, 2009. logit foreign b3. It is also referred to as the TKO rate, which is a acronym for to keep open. pdf) /S /GoToR /D (iCONTENTS) >> endobj 3 0 obj (Contents) endobj 4 0 obj /F (ig. This shows the standardized variance of the independent variables on The Roman numeral for 1 is I, 2 is II and 3 is III. 2. You can also get a service manual for your CAT Imagine that you’ve just gotten some beautiful new GE appliances. dta dataset that can be downloaded from here. Note that you can type *db ivregress* into <- See Stata 18's new features. See Cameron and Trivedi (2013;2010, chap. Quantile regression for longitudinal data. 041, a 1% increase in rainfall decreases pollution by 0. wdgmv hyzkev yyedn wjmloomh wjif aseg vkoor prrgvr zhmrp czrhn