Ivreg2 last estimates not found. ) By contrast, if > we run > > . The main extensions 1. Jul 2, 2019 · Unable to display all first-stage regressions. As the default for > ivreg2 > is to produce large sample estimates, your test results and standard > errors > will not be affected by the transformation. overidentification test. ivreg2 cinf unem, bw(3) > . This means that svy thinks that you want it to replay. It seems ivhettest does not handle factor variables. > > Phil > > > > 2010/4/6 Kit Baum <[email protected]>: > > <> > > Phil said > > > > > > I used the following ivreg2 to estimate an IV-regression, but could > > not produce the first-stage The issue was the most recent version of the reghdfe (6. Here is an example: In this example, the differences between the two sets of estimates are minimal. For ftools the distribution date was Austin, Thank you for your reply! Yes, I was under that impresssion. prais cinf unem we obtain different estimates and standard errors. reg cinf unem all yield exactly the same coefficient estimates. time it shows the elapsed time at different steps of the estimation. aweights, fweights, iweights, and pweights are allowed; see [U] 11. is the last version of ivreg2 which runs on Stata 8. Jun 29, 2017 · Hi, Is there any way of saving the first stage coefficients from ivreg2 to a dta. On Thu, Jul 15, 2010 at 10:20 AM, xueliansharon < xuelianstata@gmail. 3). When used, absorb() will also activate the small, noconstant and nopartialsmall options of ivreg2 (basically to force small sample adjustments, which are required as we might have a substantial number of fixed effects). When installing ivreg2 the first time, I used find it and then installed one of the available options. In other words, can I still include fixed effect with cross-section group without using dummy variable approach with xi:ivreg2 Sep 17, 2014 · Hmm, not sure why this didn't work for me the first time, but thanks. Jan 19, 2015 · In this version: ivreg2 now supports factor variables, and can be used for ordinary least squares (OLS) estimation using the same command syntax as Stata's official regress and newey. But the "savefirst“ option of ivreg2 could actually store the first stage result, so it's easy for ivreg2 to export it. All varlists may contain time-series operators, but factor variables are not currently supported; see help varlist. May 26, 2023 · 26 May 2023, 05:22. 1 and 2 are treatments, 3 is control. Oct 6, 2023 · I got the following error: Code: command ivreg2 is unrecognized. So I will show you my example, including the command and its output, which doesn't have this problem. Hello everyone, I use this code using the data panel, but the results don't come out and it says that Unable to display first-stage estimates; macro e (first) is missing. 5e+08 Prob > F = 0. ado file where it references that command. "estimation result not found" (Should have mentioned that) My instrument is a variable with 3 values (1, 2, 3). Mar 6, 2024 · 发表回复. This seems to be related to line 2285 in the ivreghdfe. ajuste should not be using the svy prefix if you want. net install reghdfe, from(https://raw. ivreg2+reghdfe) - Issues · sergiocorreia/ivreghdfe Nov 22, 2019 · Problem with sureg: last estimates not found. reg cinf unem > > all yield exactly the same coefficient estimates. 0. I think the "last estimates not found" error I'm getting traces to a reghdfe, requirements call. ivhettest not working after ivreg2 02 Jan 2017, 17:02. The spirit is right, but you need to pass the contents of depvar as well. ) estat weakrobust performs tests of the form 1 = r1, where r1 is a constant vector of the same dimension as 1. To match the HAC SE estimates of -newey- or -newey2 That is, > > . If you want to be sure, run two regressions, one with the variable as endogenous and one with it as exogenous, and do a difference-in-Sargan (or difference-in-J) by hand. Just in case you need it, here is what I did: *download the zip file from the repository. 93. particularly useful when the user has a rank-deficient estimate of the covariance matrix of orthogonality conditions (common with the cluster option and single-ton dummy variables). 8995 May 2, 2002 · But analysts’ optimism and use of less sophisticated valuation methods have been found to impede target price informativeness. The k variables in varlist1 and varlist2 comprise X. corr. Let’s fit a predicted curve to this plot to further investigate. It also allows you to accept potential citations to this item that we are uncertain about. Description. Although user could add "savefirst" option in xtivreg2 command, and it runs without an error, it still no result is stored like "ivreg2 xxx, savefirst" does. In any case, when you have such interactions, you' may want to use margins to examine the influence of dy/x2 (which is b2 + b3*x1) at different values of x1. To get the first stage just need to tweak the above code as: estadd scalar APF=first[7,1]: first_iq ; est restore first_iq ; estout, c(b) stats(APF) ; – user1189728. I'm not quite sure how to tell the version of each package, but here are the distribution dates from the ado describe command: For ivreghdfe the distribution date was 20211214. 6 4Feb2007 from SSC with Stata 13. If m is the number of lags you would specify in -newey- or - newey2-, then use m for the -ivregress, vce (hac nw m)- command, but n=m+1 for the -ivreg2, bw (n)- command. Simplifying your code as suggested by @Nick Cox is best, however, to answer your question the solution is below: main do-file. version (#) reghdfe has had so far two large rewrites, from version 3 to 4, and version 5 to version 6. F( 6, 62) = 1045. 0 and I am getting two errors 1) return code 111, that is one of the independent variables in the previously issued estimation command is not found during the execution of -ivhettest-. In the command pane: rvfplot, yline(0) As the scatter of this plot is not uniform, it indicates heteroskedasticity in the model. With -ivreg2- it runs ok! but the answer is not entirely satisfactory: > ivhettest supports ivreg, ivreg2 and regress but not ivregress (see the > help file Apr 22, 2024 · Stata Commands for Instrumental Variables. Re: st: overid after ivregress. 12. ivreg2 cinf unem > . lclogit2 and nlcom - "last estimates not found" 24 May 2023, 07:19. Last edited by Marry Lee; 06 Oct 2023, 03:21 . We limit our exposition here to the linear case, which is what ivreg2 Sep 8, 2021 · I reran -ivregress- without the cluster option, and you were right, SEs are almost the same as that with -ivreghdfe-, which proves my suspicion that the command "vce (cluster id )" of -ivreghdfe- fail to implement what it is supposed to do. perfect and coeflegend do not appear in the dialog box. I then installed ivregdhfe and everything worked perfect. Feb 20, 2010 · Luckily, a routine for first-stage F-stats in models with multiple endogenous variables is now programmed in ivreg2 . Prob > F = 0. DfBeta is a postestimation command. To get around. (The standard errors are a little different across most but not all of these. 9. Warning: estimated covariance matrix of moment conditions not of full rank. (The standard errors > are a little different across most but not all of these. com/serg The estimates of 1, 2, 1, and 2 can be tested for consistency with a null hypothesis about 1, our parameter of interest. And by "post" it means that it'd only work if there was an estimation performed in the first place. ivreg2 cinf unem . I have a panel with the following structure: N=6 T=53 (monthly data). ivreg2 may be used with time-series or panel data, in which case the data must be tsset before using ivreg2; see help tsset. It works for the above (#20) two sets of 2SLS regressions (attachment Result#22). Corpus ID: 117279769; XTOVERID: Stata module to calculate tests of overidentifying restrictions after xtreg, xtivreg, xtivreg2, xthtaylor @article{Schaffer2006XTOVERIDSM, title={XTOVERID: Stata module to calculate tests of overidentifying restrictions after xtreg, xtivreg, xtivreg2, xthtaylor}, author={Mark E. fitted. Note that, unlike the command ivqreg written by Do Won Kwak, ivqreg2 does not implement the estimator Martin and Mark, many thanks for the kind explanation. Jun 11, 2014 · The call to ajuste looks like replay syntax to svy. When calculating the delta for beta=0, the command I use is: psacalc delta variable_of_interest. Naturally, the standard errors of my second stage regression do aweights are not allowed with the jackknife prefix; see[R] jackknife. 0 after uninstalling every package. We found no effect on special education If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. r(199); Edit: the same model is estimated with no problems in Stata 14. parameter estimates. 11 22Nov2019 *! authors cfb & mes *! see end of file for version comments * Variable naming: * lhs = LHS endogenous * endo = X1, RHS endogenous (instrumented) = #K1 * inexog = X2 = Z2 = included exogenous (instruments) = #K2 = #L2 * exexog = Z1 = excluded exogenous (instruments) = #L1 * iv = {inexog exexog} = all instruments * rhs = {endo inexog} = RHS regressors * no 0 or 1 at Aug 5, 2019 · Note this doesn't change the estimates substantively. Here is a work-around using Clint's example: . ster not found; • last estimates not found; • 求助 使用循环命令显示last estimates not found怎么办; • 新手求教，请问输入rvfplot，yline（0）之后报错显示last estimates not found; • 用stata估计残差的时候，出现last estimates not found是为 The last two sections provide a summary of ivreg2 estimation options and syntax diagrams for all programs in the extended ivreg2 suite. I am so glad you pointed this out. Underidentification test (Anderson canon. The estimators we have discussed are available from Baum, Schaffer and Stillman’s ivreg2 package (ssc describe ivreg2). ) By contrast, if we run . 6 weight. The discrepancies vanish when I use the noconstant option. You can help adding them by using this form . As you point out, it takes some effort or experimentation to extract this information from the - ivreg2- help file. This module estimates the structural quantile functions defined by Chernozhukov and Hansen (2008) using the method of Machado and Santos Silva (forthcoming in the Journal of Econometrics ). prais cinf unem > > we obtain different estimates and standard errors. Andrew Musau. 2. I am trying to estimate the impact of opinion polls over the frequency of tweets about inequality by 6 parties. " OVERID: Stata module to conduct postestimation tests of overidentification ," Statistical Software Components S396902, Boston College Department of Economics, revised 29 Sep 2020. 非常感谢，我有点忘了，稍微再看一下该指令说明， 再对应楼主是问"面板"情况，您说的应该是对的 (我当初可能没注意楼主问的是面板资料情况)。. More information below: New versions of and extensions to the Baum-Schaffer-Stillman packages. 2 IV and GMM estimation GMM was introduced in Hansen (1982). Writing an xtivreg2 program which does this all automatically is on my to-do list but I am not sure how soon I will have time to do it. My apologies. 0g esample() from estimates store And savefirst with xtivreg2 does not create a corresponding variable. Dear all, I’m doing a IV regression with the endog (varlist_en) option and cluster at country level. 这是加了absorb的↓这是不加的↓,经管之家 (原人大经济论坛) As the default for ivreg2 is to produce large sample estimates, your test results and standard errors will not be affected by the transformation. Here is an Christopher F Baum & Vince Wiggins & Steven Stillman & Mark E Schaffer & Frank Windmeijer, 1999. Most time is usually spent on three steps: map_precompute (), map_solve () and the regression step. Additional features include: Andrea, -ivendog- isn't equipped (yet?) to handle -xtivreg2-. Hi all Feb 2, 2022 · When I run ivreg2 y (x=z), small in Stata the results seem alike. But you don't show us the exact command you used or the output provided by ivregress. ivreg2 is compatible with Stata version 10. May 20, 2020 · Dear Andrew: Thank you! Even if I use outreg2 and ivreg2 I get into trouble. When MYSELF estimate a simple 2SLS model with ivregress (or ivreg) and ivreg2, I gain discrepant estimates. bvid1 to create a dummy for each groups, it is not very feasible. 2. 0 Aug 12, 2016 · Or instead if someone know how to export the results of instrumental variable regression both first and second stages with ivgress 2sls or ivreg2 please help me. The call to clear prior to calling estimates use drops the dataset from memory. Show. github install sergiocorreia/reghdfe, version ("5. estimation results instead of perform the estimation. Schaffer and Steven Stillman}, journal={Statistical Software Components}, year={2006 Jun 13, 2022 · Estimates efficient for homoskedasticity only Statistics robust to heteroskedasticity and clustering on ts and kernel-robust to common correlated disturbances (Driscoll-Kraay) kernel=Bartlett; bandwidth=1 time variable (t): ts group variable (i): id Number of clusters (ts) = 40 Number of obs = 578 F( 88, 39) = 1. ivreg cinf unem > . If I want to make a MS Word Table of four sets of 2SLS regressions, It would not work. a vector of predicted means. This allows to link your profile to this item. But they are very large in more complex examples. Mar 7, 2007 · Abstract. ssc install github. Although I estimate a simple 2SLS exemplar with ivregress (or ivreg) and ivreg2, I get dissimilar estimates. And I have two questions when implementing this: (1) Negative Delta. I have included several packages using the ssc install and find it commands. 1 - Windows machine). This will not work for estimating a random effects iv model. Weak identification test (Cragg-Donald Wald F statistic): 31. ivreg28 provides extensions to Stata's official ivreg and newey. *! ivreg2 4. I am very new to Stata and have worked through the book "Data Analysis Using Stata" and read tons of info online but I am still not clear on a lot of things. Nov 12, 2023 · ivreghdfe is crashing on me unless I revert to reghdfe version 5. 使用ivregdhfe,不加absorb命令可以正常回归，但是加上之后一直报错，请各位老师帮忙看看这是怎么回事呢！. Sep 19, 2015 · ivreg2 with partial option. This one's easy to answer, but the answer is not entirely satisfactory: ivhettest supports ivreg, ivreg2 and regress but not ivregress (see the help file). IV estimation as a GMM problem. Here is to Cheers, Mark > Also, one mystery is that I used the same syntax in another > project last night, it did work. Before discussing further the motivation for various weak instrument diagnostics, we define the setting for IV estimation as a Generalized Method of Moments (GMM) optimization problem. Saved Results reported. I am an Economist at the Federal Reserve Board. I can save residuals from reghdfe without a problem. In the meantime, you can use ivreg or ivreg2 to do the estimation. what's the reason? > > Once again, many thanks. Dec 16, 2014 · marginsplot looks for formats, labels, and value labels attached to the variables. hascons, vce(), noheader, depname(), and weights are not allowed with the svy prefix; see[SVY] svy. (I only can export result of first stage with ivregress2 by outreg2, I did search and read a lot on the internet but I still can't do with ivreg2 and ivregress by estout package ) I'm after Stata 13. The minimum eigenvalue should be compared to Dec 9, 2018 · Thanks to Kit Baum, ivqreg2 is now available in SSC. This will not work for > estimating a random effects iv model. regression. As you note, the saved first-stage estimation with ivreg2 creates an esample() variable: storage display value variable name type format label variable label ----- _est__ivreg2_ys byte %8. LIML is a k-class estimator with k=the LIML eigenvalue lambda; 2SLS is a k-class estimator with k=1; OLS is a k-class esimator with k=0. I The newest version of ivreg2 incorporates additional code to compute eigenvalues of G T before reporting other estimates. LM statistic): 58. 1. FYI, official ivreg is still available in Stata 10 and Stata 11: -help ivreg Aug 23, 2018 · I also encountered a problem when trying to estimate IV with regdhfe. ) is derived from and supersedes the Aug 3, 2022 · 1. My main research interests are in Empirical Banking and Corporate Finance. values. 13. Let’s add a line to confirm. residuals. Try dropping one or more estimation results using -estimates drop-, using the -savefprefix- option, or using shorter variable names. github. Ben Jann's -center- command is very handy for demeaning. 07 *! see end of file for version comments program define actest9, rclass sortpreserve version 9. Given that T>N, I discarded FE model in favour of Zellner's seemingly unrelated regressions (sureg). May 15, 2019 · // set up some example data sysuse auto, clear drop if missing(rep78) // run the regressions on the sample data levelsof rep78, local(rep) levelsof foreign, local(fgn) generate res = . 074 (ie. For this reason, marginsplot needs. The same update includes other useful routines, like two-way clustering. Unlike ivreg2 or ivregress, ivreg2h allows the syntax ivreg2h depvar exogvar (endogvar=), as after augmentation with the generated regressors, the order condition for identification will be satisfied. e. Jul 23, 2014 · When I estimate a simple 2SLS model with ivregress (or ivreg) and ivreg2, I get discrepant estimates. 988801 Centered R2 = 0. Something for my (unfeasibly long) to-do list. • Several advanced options, including options that will speed up estimation using ivreg2 by suppressing the calculation of various checks and statistics. However, I get a different error code invsym(): matrix has Sep 14, 2021 · I would like to reconfirm my interpretation of the post estimationn results: 1. the dataset you used to produce the margins results. The standard regression functionality (parameter estimation, inference, robust covariances, predictions, etc. Handle: RePEc:boc:bocode:s396802. You can browse but not post. ivreg2 cinf unem, bw(3) . ivreg returns an object of class "ivreg", with the following components: coefficients. I switched back to reghdfe 5. This code just modifies ivreg2 adding an absorb() option that uses reghdfes Mata functions (see this link for the line-by-line differences). Specifically, I am using psacalc for this practice. 13 22Jan2015 *! based on actest 2. I use Stata. Then estmate using -ivreg2-, and test using -ivhettest-. All Time Today Last Week Last Month. aweights are not allowed with the jackknife prefix; see[R] jackknife. The resulting estimates are saved in the ereturn list and as a set of estimates named GenInst. However, when I try to run the DMEXOGXT command after running the XTIVREG2, which I use insteda of XTIVREG, since I want to use robust and cluster, DMEXOGXT does not work and I get the following message; dmexogxt only works after xtivreg, fe last estimates not found r(301); 2) Is there an equivalent command for IVHETTEST for panel data after Jan 1, 2010 · Estimates indicate that a child's exposure to higher NC Pre-K funding was positively associated with that child's academic achievement 6 years later. stata用ivreghdfe命令的时候报错last estimates not found,求助！. used to produce the margins results. The overidentifying restrictions test reported after LIML estimation is the Anderson-Rubin (1950) overidentification statistic in a homoskedastic context. In the command pane: Aug 22, 2023 · For ivreg2 I installed using ssc install ivreg2. Check out the help file examples of -ivreg2-, and you'll see an example in the list of how to mimic a Durbin-Wu-Hausman endogeneity test using this option. Hope For simple status reports, set verbose to 1. Therefore I create (ib3. Jun 4, 2015 · First, the title should have read xtivreg2 instead of ivreg2. thank you in advance. 1 or later. The F-stat is usually compared to critical value thresholds given in Stock and Yogo (2005), which are helpfully provided in the output of ivreghdfe/ivreg2, rather than reported as a p-value. Dear Mark, Thank you for your prompt answer I updated my versions of ivreg2 and ranktest as you suggested. . ivreg2: As a user-created command, ivreg2 extends the functionality of ivregress. These are reported by the Stata program ivreg2 when the ffirst option is specified, and include the partial R2 and first-stage F-statistics on excluded instruments. eststo model_1: regress short_phys ever_attend_tk, vce (robust) May 12, 2020 · As the description of xtivreg2 says, it is the wrapper of ivreg2. Nov 18, 2023 · Run IV/2SLS with many levels of fixed effects (i. ivreg2 provides extensions to Stata's official ivregress and newey. 19 Sep 2015, 03:30. See log below. Feb 6, 2019 · However, I have more than 3000 groups, if I simply use i. | Robust. weights. reghdfe is a generalization of areg (and xtreg,fe, xtivreg,fe) for multiple levels of fixed effects (including heterogeneous slopes), alternative estimators (2sls, gmm2s, liml), and additional robust standard errors (multi-way clustering, HAC standard errors, etc). ) an indicator that is 1 for 1 and 1 for 2. 0000. do. It provides additional features, such as testing for endogeneity, weak instruments, and overidentification. com > wrote: > Dear all, I am using -ivhettest- by Mark E. 2 syntax [varlist(default=none ts)] [if] [in] [aw fw pw iw] /// [, LAGs(numlist integer>0 sort) STRICTexog q0 bp small /// Robust CLuster(varlist) BW(string) kernel Jul 4, 2019 · I worked it out by two ways: mata and chi2 test: Here's my codes: *. 3. I've tried uninstalling everything (ftools, reghdfe, ivreghdfe) and reinstalling from github to no avail. I have literally the exact same lines of code above in my question. However, I like to implement three-way clustering, but ivregdhfe only supports two-way clustering because it is based on ivreg2. this, just add a required argument to ajuste. The plot also appears to show a curve. 08. One catch: as usual, when doing fixed effects using the demeaning transform, the reported standard errors and statistics using the demeaned data will have the wrong degrees of freedom because the program reporting the results doesn the command gmm estimates parameters by GMM you can specify the moment conditions as substitutable expressions a substitutable expression in Stata is like any mathematical expression, except that the parameters of the model are enclosed in braces {} alternatively, you may use command program to create a The ` variables in varlist1 and instlist comprise Z, the matrix of instruments. it to work properly with svy bootstrap. Its main capabilities: two-step feasible GMM estimation; continuously updated GMM estimation (CUE); LIML and k-class estimation; automatic 面板数据DWH的命令不是这个吧，stata提示：ivendog works only after ivreg, ivreg2; use dmexogxt after 1. 0000 Total (centered) SS = 2033. 12 and livreg2 Mata library 1. However, you have an easy alternative, which is to use the -orthog()- option of -xtivreg2- to conduct your endogeneity tests. ivreg2, xtivreg2, ranktest and xtoverid, and a new program Not sure what the problem is. May 24, 2023 · You are not logged in. 不过，就如同我 May 29, 2019 · I'm running ivreghdfe with 3 fixed effects and trying to save the residuals. We have no bibliographic references for this item. Dear fellow Stata users, I installed Stata in a new computer. ivreg cinf unem . We consider the model. ivregress: ivregress is a built-in command provided by Stata for instrumental variables regression. However, the overidentification statistic and the Durbin-Wu-Hausman statistic can’t be reported because. Anyway, this works. Thu, 15 Jul 2010 16:36:51 -0500. Sep 8, 2016 · Problem with ivreg2 (struct ms_vcvorthog undefined) 08 Sep 2016, 08:24. (In practice, the exogenous covariates X2 are partialled out for simplicity. file? I am using regsave for the second stage coefficients, but even after reading similar post here on Statalist I can't find out how to do it for the first stage? I had the same sets of code for 4 different sets of residuals I was trying to create and all ran until the last one and it is now stuck on 2008 and 2009 like the above code was. -ivregress- is "too new" for -overid-. (1) 2SLS, IVs: iv_prefect0522 iv_05prob2 eststo clear foreach var of varlist y* I'm using Stata 13. Oct 14, 2019 · Thank you. 回帖后跳转到最后一页. Besides, -help ivregress. foreach r of local rep { foreach f of local fgn { capture regress weight length if rep78==`r' & foreign==`f' if _rc != 0 display "FAILURE rep78 `r' foreign `f' return code " _rc else { quietly predict temp May 31, 2021 · The ivreg package (by John Fox , Christian Kleiber, and Achim Zeileis) provides a comprehensive implementation of instrumental variables regression using two-stage least-squares (2SLS) estimation. >10 and greater than all critical values) 3. Try this demo: That is, . 187 (not significant) 2. postestimation- informs that -estat overid- can be used to obtain the. 1 and ivreg2 3. Best. Schaffer, v1. a vector of residuals. last estimates not found r(301); I then installed -dmexogxt- and tried: dmexogxt lreptextg but got the following error: dmexogxt only works after xtivreg, fe last estimates not found r(301); Something similar seems to occur when I try to use the -overid, all- command, although for me this is not essential, I only use it as a check. y = Xβ + u, u ∼ (0, Ω) with X (N × k) and define a matrix Z (N × `) where ` ≥ k. There may be insufficient room to store results using -estimates store-, or names of endogenous regressors may be too long to store the results. Date. Both matrices by default include a units vector. It is now a mainstay of both econometric practice and econometrics textbooks. 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 with the instrument in place of the endogenous regressor in the structural model. 2010/4/6 Martin Weiss <[email protected]>: > > <> > > > " By the way, what's the meaning of FSRs The residuals do not appear randomly distributed. Whatever you put in -orthog ()- is what -xtivreg2- will treat as endogenous in the comparator regression. Dec 3, 2023 · • 运行“estimates use mvmeta ” 出现 file mvmeta. Tags: None. So it seems the be driven by R always using small sample corrections while Stata only using those when explicitly asked for. Stata 9 Andrea, -ivendog- isn't equipped (yet?) to handle -xtivreg2-. The results should be very close to C Mar 12, 2020 · The p-value of the F-stat (Cragg-Donald or Kleibergen-Paap), is, I think, not available. See my revised answer. That is, the do-file needs to see two arguments. 0 and it worked! Try to install an earlier version of reghdfe if you don't use Stata 16. Oct 17, 2021 · That suggests that something went wrong in the first-stage regression, perhaps. ivreg28 supports the same command syntax as official ivreg and supports (almost) all of its options. Jun 5, 2017 · Dear All, I am recently learning Oster (2016)'s approach for robustness checks with respect to unobservable selection bias. I am trying to produce a table with outreg2 for estimates using xtivreg2 (on Stata 13. *! actest9 2. I did both of these today on Stata version 18. LIML, OLS and IV/2SLS are examples of k-class estimators. Alternatively, you can explain the issue, and then discuss dy/dx2 at different values of x1. oo qr bd eh sm oi hu oa qz qp