Message-ID: <CAHrK517rKMPT+VoBSzWp08kjD=NHjzN_7GWmsmd9Excv6KVrsw@mail.gmail.com>
Date: 2011-11-09T19:32:50Z
From: John C Frain
Subject: Interpreting Multiple Linear Regression Summary
In-Reply-To: <alpine.LNX.2.00.1111091104550.17032@salmo.appl-ecosys.com>
As far as I know if there is an NA in any variable in an observation
the default is to drop the entire observation. Thus there are no
observations in your calculation
Best Regards
John
On 9 November 2011 19:17, Rich Shepard <rshepard at appl-ecosys.com> wrote:
> On Wed, 9 Nov 2011, Daniel Nordlund wrote:
>
>> I would guess that there is something problematic with the how the data
>> frame is structured relative to what lm() is expecting.
>
> Dan,
>
> ?I was not comfortable with my explanation, but the formula (and data
> frame) was equivalent to those of the other 8 streams.
>
>> So, I would not give up looking for a solution just yet.
>
> ?OK. I'm always up for learning more about R and its processes.
>
>> Can you show us the result of str() on the data frame that you attached?
>
> ?Sure. I subset the original data frame to select only the 6 predictor
> variables and the response variable. Same lm() results. I'll provide the
> data frame, too.
>
> summary(lm(formula = TDS ~ Cond + Ca + Cl + Mg + Na + SO4, data =
> mod.stump.cast))
>
> Call:
> lm(formula = TDS ~ Cond + Ca + Cl + Mg + Na + SO4, data = mod.stump.cast)
>
> Residuals:
> ALL 1 residuals are 0: no residual degrees of freedom!
>
> Coefficients: (6 not defined because of singularities)
> ? ? ? ? ? ?Estimate Std. Error t value Pr(>|t|)
> (Intercept) ? ? ?125 ? ? ? ? NA ? ? ?NA ? ? ? NA
> Cond ? ? ? ? ? ? ?NA ? ? ? ? NA ? ? ?NA ? ? ? NA
> Ca ? ? ? ? ? ? ? ?NA ? ? ? ? NA ? ? ?NA ? ? ? NA
> Cl ? ? ? ? ? ? ? ?NA ? ? ? ? NA ? ? ?NA ? ? ? NA
> Mg ? ? ? ? ? ? ? ?NA ? ? ? ? NA ? ? ?NA ? ? ? NA
> Na ? ? ? ? ? ? ? ?NA ? ? ? ? NA ? ? ?NA ? ? ? NA
> SO4 ? ? ? ? ? ? ? NA ? ? ? ? NA ? ? ?NA ? ? ? NA
>
> Residual standard error: NaN on 0 degrees of freedom
> ?(63 observations deleted due to missingness)
>
> ?str(mod.stump.cast)
> 'data.frame': ? 64 obs. of ?7 variables:
> ?$ Ca ?: num ?NA NA 24.4 NA 21.4 NA NA NA NA NA ...
> ?$ Cl ?: num ?1.58 5.6 3 NA 1 5 1.2 4 4 8.4 ...
> ?$ Cond: num ?NA NA 190 187 184 NA NA NA NA NA ...
> ?$ Mg ?: num ?NA NA 10 NA 9.1 NA NA NA NA NA ...
> ?$ Na ?: num ?NA NA NA NA NA NA NA NA NA NA ...
> ?$ SO4 : num ?9.4 6.5 9 NA 7 55 6.8 105 15.6 8.4 ...
> ?$ TDS : num ?105 181 112 144 114 308 96 430 108 108 ...
>
> summary(mod.stump.cast)
> ? ? ? Ca ? ? ? ? ? ? ?Cl ? ? ? ? ? ? ?Cond ? ? ? ? ? ? Mg ? ? ? ? ? ? ?Na
> ?Min. ? : 0.60 ? Min. ? : 1.000 ? Min. ? : ?2.2 ? Min. ? : 9.10 ? Min. ? : 4
> ?1st Qu.:23.35 ? 1st Qu.: 2.000 ? 1st Qu.:214.8 ? 1st Qu.:11.00 ? 1st Qu.: 4
> ?Median :28.35 ? Median : 4.000 ? Median :282.5 ? Median :17.40 ? Median : 4
> ?Mean ? :32.77 ? Mean ? : 4.076 ? Mean ? :294.6 ? Mean ? :17.85 ? Mean ? : 4
> ?3rd Qu.:40.55 ? 3rd Qu.: 5.600 ? 3rd Qu.:372.0 ? 3rd Qu.:22.10 ? 3rd Qu.: 4
> ?Max. ? :64.30 ? Max. ? :13.000 ? Max. ? :636.0 ? Max. ? :32.40 ? Max. ? : 4
> ?NA's ? :50.00 ? NA's ? :11.000 ? NA's ? : 42.0 ? NA's ? :51.00 ? NA's ? :62
> ? ? ?SO4 ? ? ? ? ? ? ?TDS
> ?Min. ? : ?4.00 ? Min. ? : 14.0
> ?1st Qu.: ?7.00 ? 1st Qu.:131.2
> ?Median : ?9.40 ? Median :174.0
> ?Mean ? : 16.31 ? Mean ? :176.9
> ?3rd Qu.: 17.00 ? 3rd Qu.:195.5
> ?Max. ? :105.00 ? Max. ? :430.0
> ?NA's ? : ?3.00 ? NA's ? : ?2.0
>
> ?mod.stump.cast
> ? ? Ca ? ?Cl ?Cond ? Mg Na ? SO4 TDS
> 1 ? ?NA ?1.58 ? ?NA ? NA NA ? 9.4 105
> 2 ? ?NA ?5.60 ? ?NA ? NA NA ? 6.5 181
> 3 ?24.4 ?3.00 190.0 10.0 NA ? 9.0 112
> 4 ? ?NA ? ?NA 187.0 ? NA NA ? ?NA 144
> 5 ?21.4 ?1.00 184.0 ?9.1 NA ? 7.0 114
> 6 ? ?NA ?5.00 ? ?NA ? NA NA ?55.0 308
> 7 ? ?NA ?1.20 ? ?NA ? NA NA ? 6.8 ?96
> 8 ? ?NA ?4.00 ? ?NA ? NA NA 105.0 430
> 9 ? ?NA ?4.00 ? ?NA ? NA NA ?15.6 108
> 10 ? NA ?8.40 ? ?NA ? NA NA ? 8.4 108
> 11 ? NA ?1.00 ? ?NA ? NA NA ? 8.8 125
> 12 ? NA ?1.40 ? ?NA ? NA NA ?19.4 129
> 13 ? NA ?4.90 ? ?NA ? NA NA ?37.0 360
> 14 ? NA ?1.70 ? ?NA ? NA NA ?12.0 140
> 15 ? NA ?2.00 ? ?NA ? NA NA ?10.0 ?95
> 16 ? NA ?1.60 ? ?NA ? NA NA ? 9.1 120
> 17 ? NA ?3.30 ? ?NA ? NA NA ?34.0 280
> 18 ? NA ?2.20 ? ?NA ? NA NA ?11.0 130
> 19 ? NA ?9.00 ? ?NA ? NA NA ?69.0 352
> 20 ? NA ?1.00 ? ?NA ? NA NA ?18.0 148
> 21 ? NA ?2.00 ? ?NA ? NA NA ? 9.0 107
> 22 28.0 ?1.00 248.0 11.0 ?4 ?13.0 125
> 23 32.0 1.00 ? ?NA 12.0 4 9.0 139
> 24 ? NA ?5.00 ? ?NA ? NA NA ? 7.0 188
> 25 ? NA ?4.00 ? ?NA ? NA NA ? 6.0 201
> 26 ? NA ?3.00 ? ?NA ? NA NA ? 5.0 178
> 27 ? NA ?2.27 ? ?NA ? NA NA ? 7.8 197
> 28 ? NA ?1.76 ? ?NA ? NA NA ? 7.8 187
> 29 ? NA ?5.81 ? ?NA ? NA NA ? 7.5 182
> 30 ? NA ?4.23 ? ?NA ? NA NA ? 6.0 165
> 31 ? NA ?4.23 ? ?NA ? NA NA ? 7.3 186
> 32 ? NA ?6.25 ? ?NA ? NA NA ? 7.0 191
> 33 ? NA ?6.72 ? ?NA ? NA NA ? 7.5 190
> 34 34.7 ?4.00 304.0 17.4 NA ? 6.0 176
> 35 ? NA ? ?NA 354.0 ? NA NA ? 7.0 175
> 36 42.5 ?5.00 379.0 21.1 NA ? 7.0 220
> 37 ? NA ?5.80 ? ?NA ? NA NA ? 5.6 163
> 38 26.0 ?5.80 300.0 24.0 NA ? 5.6 163
> 39 ? NA ?2.20 ? ?NA ? NA NA ? 5.4 152
> 40 ? NA ?5.40 ? ?NA ? NA NA ?11.0 221
> 41 ? NA ?5.40 ? ?NA ? NA NA ?10.5 171
> 42 ? NA ?4.80 ? ?NA ? NA NA ? 9.9 204
> 43 ? NA ?8.00 ? ?NA ? NA NA ?11.7 174
> 44 ? NA ?1.00 ? ?NA ? NA NA ? 8.4 190
> 45 ? NA ?4.80 ? ?NA ? NA NA ?12.1 174
> 46 ? NA ?5.90 ? ?NA ? NA NA ?16.0 210
> 47 ? NA ?5.90 ? ?NA ? NA NA ?20.0 190
> 48 ? NA 13.00 ? ?NA ? NA NA ? 7.6 180
> 49 ? NA ?5.60 ? ?NA ? NA NA ?17.0 200
> 50 ? NA ?1.20 ? ?NA ? NA NA ? 6.5 180
> 51 ?0.6 ? ?NA ? 2.2 ? NA NA ? ?NA ?NA
> 52 21.4 ? ?NA 187.0 ?9.5 NA ? 8.0 120
> 53 ? NA ? ?NA 285.0 ? NA NA ?22.0 135
> 54 48.3 ?3.00 378.0 22.1 NA ?24.0 228
> 55 63.5 ?7.00 533.0 29.9 NA ?44.0 ?14
> 56 ? NA ? ?NA 207.0 ? NA NA ? ?NA ?NA
> 57 ? NA ? ?NA 262.0 ? NA NA ?13.0 156
> 58 28.7 ?2.00 244.0 12.6 NA ?13.0 140
> 59 ? NA ? ?NA 238.0 ? NA NA ?12.0 128
> 60 ? NA ? ?NA 280.0 ? NA NA ?18.0 160
> 61 ? NA ? ?NA 380.0 ? NA NA ?23.0 215
> 62 ? NA ? ?NA 402.0 ? NA NA ?23.0 230
> 63 64.3 ?7.00 636.0 32.4 NA ?73.0 316
> 64 23.0 ?4.10 300.0 21.0 NA ? 4.0 163
>
> Thanks,
>
> Rich
>
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--
John C Frain
Economics Department
Trinity College Dublin
Dublin 2
Ireland
www.tcd.ie/Economics/staff/frainj/home.html
mailto:frainj at tcd.ie
mailto:frainj at gmail.com