在阅读了这个关于对比错误的答案并查看了我的数据后，我在尝试组合包“plm”和“效果”时仍然遇到问题。这可能是不可能的，因为约翰福克斯没有在他的效果文档中讨论这种可能性（显然不允许链接 - 谷歌：“约翰福克斯效果包”，如果你想看看）。因此，如果确实不可能，请告诉我。
我正在对减少的数据集进行简单回归
library(plm) ; library(effects)
shortdata<-plm.data(shortdata,index=c("ID","Year"))
MESS<-plm(paci_to_t ~ paco_to_t + cddom + cddom2,data=shortdata,model="within")
Effect(c('cddom2'),MESS)
我收到以下错误（以及典型的 plm 警告消息）
Error in `contrasts<-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) :
contrasts can be applied only to factors with 2 or more levels
我知道它仍然是一个很长的数据结构，但我认为它值得分享
> dput(shortdata)
structure(list(ID = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L,
5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L,
6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L), .Label = c("1", "2", "4", "5",
"6", "7"), class = "factor"), Year = structure(c(1L, 2L, 3L,
4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L, 1L,
2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L,
16L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L,
14L, 15L, 16L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L,
12L, 13L, 14L, 15L, 16L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L,
10L, 11L, 12L, 13L, 14L, 15L, 16L, 1L, 2L, 3L, 4L, 5L, 6L, 7L,
8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L), .Label = c("1991",
"1992", "1993", "1994", "1995", "1996", "1997", "1998", "1999",
"2000", "2001", "2002", "2003", "2004", "2005", "2006"), class = "factor"),
paco_to_t = c(47L, 45L, 50L, 61L, 113L, 76L, 60L, 70L, 75L,
70L, 52L, 39L, 29L, 34L, 12L, 12L, 1L, 4L, 6L, 34L, 42L,
25L, 38L, 34L, 30L, 27L, 32L, 27L, 7L, 5L, 0L, 0L, 14L, 33L,
38L, 36L, 33L, 24L, 22L, 25L, 28L, 65L, 59L, 44L, 49L, 43L,
27L, 15L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 2L, 3L, 13L, 22L,
11L, 12L, 2L, 1L, 3L, 7L, 11L, 31L, 53L, 24L, 28L, 29L, 22L,
38L, 41L, 47L, 40L, 30L, 21L, 8L, 9L, 14L, 59L, 79L, 129L,
78L, 91L, 112L, 86L, 104L, 101L, 140L, 83L, 35L, 17L, 13L
), paci_to_t = c(535L, 641L, 582L, 634L, 871L, 392L, 421L,
285L, 223L, 183L, 52L, 24L, 1L, 5L, 1L, 0L, 2L, 22L, 25L,
124L, 216L, 70L, 115L, 78L, 46L, 32L, 14L, 10L, 2L, 1L, 0L,
0L, 683L, 626L, 1520L, 385L, 514L, 226L, 166L, 85L, 169L,
391L, 160L, 85L, 43L, 23L, 6L, 1L, 0L, 0L, 0L, 0L, 0L, 0L,
0L, 0L, 0L, 0L, 7L, 13L, 5L, 0L, 0L, 0L, 21L, 120L, 186L,
187L, 519L, 113L, 200L, 110L, 41L, 43L, 20L, 28L, 12L, 2L,
0L, 0L, 143L, 73L, 368L, 708L, 920L, 533L, 583L, 412L, 256L,
212L, 147L, 177L, 84L, 8L, 0L, 0L), cddom = structure(c(4.22657266700715,
7.07828323739468, 5.58155937520987, 6.09945741088926, 4.98990473760187,
13.1975509132969, 5.60581022431812, 6.4115834088139, 3.19372115108478,
3.47380227675641, 4.13404916693487, 2.97544267158703, 2.54471629085273,
2.64814971815201, 1.28583544617808, 0.437627780850619, 0.136363636363636,
0.164922480620155, 0.981640399790555, 1.61119564479727, 4.27951983102512,
4.52440902710094, 2.32837056711187, 6.18186426561852, 4.0123555170895,
4.22609174210518, 3.95801989660183, 4.61957981110804, 3.77282177376164,
1.66791871414077, 0.546721420916684, 0.265624433322453, 2.41282572727806,
2.77748331046807, 7.00223921984389, 3.55837337174436, 5.31590575343992,
2.61930006177923, 2.31060371552517, 2.57360416944421, 1.84395565608465,
2.92626684365294, 3.61419385672379, 1.80034349383174, 1.50187312925546,
1.11122165051967, 0.997854809226777, 0.386006521136941, 0,
0, 0, 0, 0, 0, 0, 0, 0.0476190476190476, 0.056547619047619,
0.0696251163521699, 0.385345494115747, 0.451639377056987,
0.33059260900224, 0.347544282905224, 0.0138314176245211,
0.211351052048726, 0.525647451963241, 0.696630753538187,
0.666082288178836, 1.09492110512526, 3.8035303566375, 1.00915595031924,
0.816810004384515, 0.530090984042535, 0.554438577055268,
1.08116003643161, 0.467985507058757, 0.512281275398252, 0.833471981363938,
0.506558172321601, 0.498777213205938, 0.548336215316966,
0.85237681730237, 0.982747572848003, 6.59758768791534, 8.74094242997363,
9.29913186611362, 6.85204239723805, 7.22544455545639, 7.55800542543194,
4.85857232261679, 3.3323740421857, 3.49663263434836, 4.73578798222752,
3.12245695547519, 1.39134774182295, 0.676122574837844), .Dim = 96L, .Dimnames = list(
c("1990_ABT", "1991_ABT", "1992_ABT", "1993_ABT", "1994_ABT",
"1995_ABT", "1996_ABT", "1997_ABT", "1998_ABT", "1999_ABT",
"2000_ABT", "2001_ABT", "2002_ABT", "2003_ABT", "2004_ABT",
"2005_ABT", "1990_AKN", "1991_AKN", "1992_AKN", "1993_AKN",
"1994_AKN", "1995_AKN", "1996_AKN", "1997_AKN", "1998_AKN",
"1999_AKN", "2000_AKN", "2001_AKN", "2002_AKN", "2003_AKN",
"2004_AKN", "2005_AKN", "1990_ALL", "1991_ALL", "1992_ALL",
"1993_ALL", "1994_ALL", "1995_ALL", "1996_ALL", "1997_ALL",
"1998_ALL", "1999_ALL", "2000_ALL", "2001_ALL", "2002_ALL",
"2003_ALL", "2004_ALL", "2005_ALL", "1990_ABT", "1990_ABT",
"1990_ABT", "1990_ABT", "1990_ABT", "1990_ABT", "1990_ABT",
"1990_ABT", "1998_ALT", "1999_ALT", "2000_ALT", "2001_ALT",
"2002_ALT", "2003_ALT", "2004_ALT", "2005_ALT", "1990_AMG",
"1991_AMG", "1992_AMG", "1993_AMG", "1994_AMG", "1995_AMG",
"1996_AMG", "1997_AMG", "1998_AMG", "1999_AMG", "2000_AMG",
"2001_AMG", "2002_AMG", "2003_AMG", "2004_AMG", "2005_AMG",
"1990_AZN", "1991_AZN", "1992_AZN", "1993_AZN", "1994_AZN",
"1995_AZN", "1996_AZN", "1997_AZN", "1998_AZN", "1999_AZN",
"2000_AZN", "2001_AZN", "2002_AZN", "2003_AZN", "2004_AZN",
"2005_AZN"))), cddom2 = structure(c(17.8639165094919,
50.1020935887824, 31.1538050589932, 37.2033807072519, 24.8991492903416,
174.175350109063, 31.4251082710696, 41.1084018081777, 10.1998547908863,
12.067302257998, 17.0903625146349, 8.85325909190098, 6.47558100093125,
7.01269692974855, 1.65337279464797, 0.191518074572238, 0.018595041322314,
0.0271994246139054, 0.96361787450096, 2.5959514058137, 18.3142899841373,
20.4702770445124, 5.42130949779285, 38.2154457985312, 16.0989967955186,
17.8598514126896, 15.665921501896, 21.340517631197, 14.2341841365699,
2.78195283698102, 0.298904312089158, 0.0705563395778743,
5.8217279902149, 7.71441353992869, 49.03135409192, 12.6620210527394,
28.2588539794557, 6.86073281363667, 5.33888953019871, 6.6234384209806,
3.40017246160656, 8.56303764026254, 13.06239723398, 3.24123669578228,
2.2556228963796, 1.23481355658365, 0.995714220297008, 0.149001034360244,
0, 0, 0, 0, 0, 0, 0, 0, 0.00226757369614512, 0.00319763321995465,
0.0048476568270532, 0.148491149835309, 0.203978126908423,
0.109291473126908, 0.120787028580106, 0.000191308113503912,
0.0446692672021035, 0.276305243755448, 0.485294406775182,
0.443665614625554, 1.19885222644872, 14.466843173863, 1.01839573206472,
0.667178583262631, 0.280996451363183, 0.30740213572707, 1.16890702437679,
0.219010434817042, 0.26243210512366, 0.694675543718729, 0.2566011819458,
0.248778708413482, 0.300672605028135, 0.726546238674519,
0.965792791938642, 43.528163299732, 76.4040745641133, 86.4738534633698,
46.9504850135478, 52.2070490239743, 57.1234460108586, 23.6057250140979,
11.104716757033, 12.2264397795899, 22.4276878126106, 9.74973743879538,
1.93584853867582, 0.457141736205356), .Dim = 96L, .Dimnames = list(
c("1990_ABT", "1991_ABT", "1992_ABT", "1993_ABT", "1994_ABT",
"1995_ABT", "1996_ABT", "1997_ABT", "1998_ABT", "1999_ABT",
"2000_ABT", "2001_ABT", "2002_ABT", "2003_ABT", "2004_ABT",
"2005_ABT", "1990_AKN", "1991_AKN", "1992_AKN", "1993_AKN",
"1994_AKN", "1995_AKN", "1996_AKN", "1997_AKN", "1998_AKN",
"1999_AKN", "2000_AKN", "2001_AKN", "2002_AKN", "2003_AKN",
"2004_AKN", "2005_AKN", "1990_ALL", "1991_ALL", "1992_ALL",
"1993_ALL", "1994_ALL", "1995_ALL", "1996_ALL", "1997_ALL",
"1998_ALL", "1999_ALL", "2000_ALL", "2001_ALL", "2002_ALL",
"2003_ALL", "2004_ALL", "2005_ALL", "1990_ABT", "1990_ABT",
"1990_ABT", "1990_ABT", "1990_ABT", "1990_ABT", "1990_ABT",
"1990_ABT", "1998_ALT", "1999_ALT", "2000_ALT", "2001_ALT",
"2002_ALT", "2003_ALT", "2004_ALT", "2005_ALT", "1990_AMG",
"1991_AMG", "1992_AMG", "1993_AMG", "1994_AMG", "1995_AMG",
"1996_AMG", "1997_AMG", "1998_AMG", "1999_AMG", "2000_AMG",
"2001_AMG", "2002_AMG", "2003_AMG", "2004_AMG", "2005_AMG",
"1990_AZN", "1991_AZN", "1992_AZN", "1993_AZN", "1994_AZN",
"1995_AZN", "1996_AZN", "1997_AZN", "1998_AZN", "1999_AZN",
"2000_AZN", "2001_AZN", "2002_AZN", "2003_AZN", "2004_AZN",
"2005_AZN")), class = "AsIs")), .Names = c("ID", "Year",
"paco_to_t", "paci_to_t", "cddom", "cddom2"), class = c("plm.dim",
"data.frame"), row.names = c(1L, 2L, 3L, 4L, 160L, 5L, 162L,
163L, 164L, 6L, 166L, 7L, 8L, 9L, 170L, 171L, 172L, 173L, 174L,
175L, 176L, 177L, 178L, 179L, 180L, 181L, 182L, 183L, 184L, 10L,
186L, 11L, 188L, 12L, 190L, 191L, 192L, 13L, 194L, 14L, 196L,
197L, 15L, 199L, 200L, 16L, 202L, 17L, 157L, 400L, 401L, 583L,
524L, 565L, 526L, 527L, 204L, 205L, 206L, 207L, 208L, 209L, 210L,
211L, 212L, 213L, 214L, 215L, 216L, 217L, 218L, 18L, 19L, 221L,
222L, 223L, 224L, 20L, 226L, 21L, 22L, 23L, 230L, 231L, 232L,
233L, 234L, 235L, 236L, 237L, 238L, 239L, 24L, 25L, 26L, 27L))
现在尽我所能，我没有看到小于 2 个级别的因素，所以我不明白这个错误来自哪里。我使用 effects 包的最终目标是能够在我的响应变量上绘制 cddom（和 cddom2，它是 cddom 的平方版本）的边际效应。当然，在我的完整数据集中，我还有大约 15 个控件，它们都不是单一级别的因素，但我一直遇到同样的问题。
我希望有人可以建议！
编辑效果功能的这个问题有时会发生变化。例如
Effect(c("cddom","cddom2"),MESS)
给出以下错误
Error in mod.matrix %*% mod$coefficients[!is.na(coef(mod))] : non-conformable arguments
提前致谢
西蒙