cases <- c(465, 463,    866,    475,    1023,   917,    913,    1239,   1050,   1065,   1293,   1203,   912,    1431, 896,  1176,   1305)
plot(cases)

aveJUneTemp <- c(66.1,  69.1,   71.1,   68.2,   65.5,   73.4,   71, 72.7,   68.7,   67.7,   69.3,   69.5,   72.3,   68.9,   69.5,   69.7,   71.3)
aveJulyTemp <- c(72.4,  75.9,   77, 73.7,   72.2,   76.8,   79.7,   76, 75.6,   70, 76.3,   78.8,   80.2,   75, 71.5,   73.4,   75.5)
aveAugTemp <- c(72.2,   74.2,   70.9,   75.3,   66.3,   71.7,   72.1,   72.1,   72.5,   69.5,   77, 73.6,   72, 74.7,   73.3,   70.7,   73.4)
aveTotalTemp <- ((aveJUneTemp + aveJulyTemp + aveAugTemp)/3)
plot(aveTotalTemp)

totJuneRain <- c(4.56,  6.35,   8.3,    4.66,   3.06,   4.24,   2.81,   2.05,   2.7,    2.86,   6.25,   5.28,   2.59,   5.13,   11.36,  4.4,    4.49)
totJulyRain <- c(6.1,   2.12,   5.19,   2.05,   3.36,   2.94,   1.29,   3.29,   2.13,   2.17,   3.03,   5.23,   4.9,    3.51,   2.27,   7.32,   5.09)
totAugRain <- c(3.19,   2.31,   8.3,    1.12,   1.19,   5.22,   6.9,    9.32,   3.35,   6.43,   4.91,   3.03,   1.38,   2.07,   2.9,    2.99,   7.82)
totalRain <- (totJuneRain + totJulyRain + totAugRain)
plot(totalRain)

DIJune <- c(0,  3,  0,  1,  0,  2,  0,  -3, 0,  0,  0,  3,  0,  2,  3,  0,  0)
DIJuly <- c(1,  2,  2,  1,  1,  2,  -2, -3, 0,  0,  1,  3,  -2, 0,  3,  0,  2)
DIAug <- c(2,   0,  3,  0,  1,  1,  -2, -3, 0,  0,  2,  0,  -3, 0,  3,  0, 3)
HDD <- c(6660,  8074,   6845,   7686,   7407,   6974,   6611,   7035,   7937,   7773,   7002,   7709,   5852,   7708,   8597,   7528,   6283)
TotalSnow <- c(36.2,    75.8,   66, 35, 66.3,   25.5,   44.4,   35.5,   44.9,   45, 40.7,   86.6,   22.3,   67.7,   69.8,   32.4,   36.7)
library(MASS)
mymod <- lm(cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + HDD + TotalSnow)
summary(mymod)
## 
## Call:
## lm(formula = cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + 
##     DIAug + HDD + TotalSnow)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -452.27 -197.82    7.38  179.15  361.94 
## 
## Coefficients:
##                Estimate Std. Error t value Pr(>|t|)
## (Intercept)  -3.295e+03  5.479e+03  -0.601    0.562
## aveTotalTemp  4.969e+01  6.875e+01   0.723    0.488
## totalRain     3.713e+00  3.722e+01   0.100    0.923
## DIJune       -5.295e+01  1.309e+02  -0.404    0.695
## DIJuly       -8.627e+01  1.646e+02  -0.524    0.613
## DIAug         6.381e+01  1.259e+02   0.507    0.624
## HDD           6.351e-02  1.852e-01   0.343    0.739
## TotalSnow     4.723e+00  6.792e+00   0.695    0.504
## 
## Residual standard error: 353.5 on 9 degrees of freedom
## Multiple R-squared:  0.1947, Adjusted R-squared:  -0.4316 
## F-statistic: 0.3109 on 7 and 9 DF,  p-value: 0.9312
stepAIC(mymod, direction = "backward")
## Start:  AIC=204.7
## cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + 
##     HDD + TotalSnow
## 
##                Df Sum of Sq     RSS    AIC
## - totalRain     1      1244 1126046 202.72
## - HDD           1     14701 1139503 202.92
## - DIJune        1     20448 1145250 203.00
## - DIAug         1     32101 1156902 203.18
## - DIJuly        1     34331 1159133 203.21
## - TotalSnow     1     60422 1185224 203.59
## - aveTotalTemp  1     65292 1190093 203.66
## <none>                      1124802 204.70
## 
## Step:  AIC=202.72
## cases ~ aveTotalTemp + DIJune + DIJuly + DIAug + HDD + TotalSnow
## 
##                Df Sum of Sq     RSS    AIC
## - HDD           1     14701 1140747 200.94
## - DIJune        1     29867 1155913 201.16
## - DIJuly        1     34008 1160054 201.22
## - DIAug         1     47879 1173925 201.43
## - TotalSnow     1     75359 1201405 201.82
## - aveTotalTemp  1    105448 1231494 202.24
## <none>                      1126046 202.72
## 
## Step:  AIC=200.94
## cases ~ aveTotalTemp + DIJune + DIJuly + DIAug + TotalSnow
## 
##                Df Sum of Sq     RSS    AIC
## - DIJune        1     20579 1161325 199.24
## - DIJuly        1     33855 1174602 199.44
## - DIAug         1     43095 1183842 199.57
## - aveTotalTemp  1     92536 1233283 200.26
## - TotalSnow     1    113805 1254552 200.55
## <none>                      1140747 200.94
## 
## Step:  AIC=199.24
## cases ~ aveTotalTemp + DIJuly + DIAug + TotalSnow
## 
##                Df Sum of Sq     RSS    AIC
## - aveTotalTemp  1     80941 1242267 198.39
## - TotalSnow     1     98162 1259488 198.62
## - DIAug         1    122262 1283588 198.94
## <none>                      1161325 199.24
## - DIJuly        1    193058 1354383 199.86
## 
## Step:  AIC=198.39
## cases ~ DIJuly + DIAug + TotalSnow
## 
##             Df Sum of Sq     RSS    AIC
## - TotalSnow  1     67902 1310169 197.29
## - DIAug      1     72272 1314539 197.35
## - DIJuly     1    146052 1388319 198.28
## <none>                   1242267 198.39
## 
## Step:  AIC=197.29
## cases ~ DIJuly + DIAug
## 
##          Df Sum of Sq     RSS    AIC
## - DIAug   1     38850 1349018 195.79
## - DIJuly  1     82270 1392438 196.33
## <none>                1310169 197.29
## 
## Step:  AIC=195.79
## cases ~ DIJuly
## 
##          Df Sum of Sq     RSS    AIC
## - DIJuly  1     47790 1396808 194.38
## <none>                1349018 195.79
## 
## Step:  AIC=194.38
## cases ~ 1
## 
## Call:
## lm(formula = cases ~ 1)
## 
## Coefficients:
## (Intercept)  
##       981.9
mymod2 <- lm(cases ~ aveJUneTemp  + aveJulyTemp + aveAugTemp + totJuneRain + totJulyRain + totAugRain + DIJune + DIJuly + DIAug + HDD + TotalSnow)
summary(mymod2)
## 
## Call:
## lm(formula = cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + 
##     totJuneRain + totJulyRain + totAugRain + DIJune + DIJuly + 
##     DIAug + HDD + TotalSnow)
## 
## Residuals:
##       1       2       3       4       5       6       7       8       9 
## -238.40 -363.96 -186.32 -117.71   92.81  -35.37   43.48  -81.55 -128.09 
##      10      11      12      13      14      15      16      17 
##  200.41  352.98  239.75   76.35  -34.15  128.24   65.20  -13.67 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)  
## (Intercept) -1.361e+04  7.042e+03  -1.932   0.1112  
## aveJUneTemp  1.951e+02  1.096e+02   1.780   0.1351  
## aveJulyTemp -4.360e+01  7.841e+01  -0.556   0.6022  
## aveAugTemp   4.469e+01  4.706e+01   0.950   0.3859  
## totJuneRain -1.735e+02  8.334e+01  -2.081   0.0919 .
## totJulyRain  5.590e+01  6.268e+01   0.892   0.4133  
## totAugRain  -5.890e+01  7.223e+01  -0.815   0.4519  
## DIJune      -2.630e+00  1.489e+02  -0.018   0.9866  
## DIJuly      -2.573e+02  1.730e+02  -1.487   0.1971  
## DIAug        3.008e+02  1.604e+02   1.875   0.1196  
## HDD          1.427e-01  2.833e-01   0.504   0.6359  
## TotalSnow    1.888e+01  1.111e+01   1.699   0.1501  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 323.4 on 5 degrees of freedom
## Multiple R-squared:  0.6257, Adjusted R-squared:  -0.1977 
## F-statistic: 0.7599 on 11 and 5 DF,  p-value: 0.6739
stepAIC(mymod2, direction = "backward")
## Start:  AIC=199.67
## cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + totJuneRain + 
##     totJulyRain + totAugRain + DIJune + DIJuly + DIAug + HDD + 
##     TotalSnow
## 
##               Df Sum of Sq    RSS    AIC
## - DIJune       1        33 522835 197.68
## - HDD          1     26530 549332 198.51
## - aveJulyTemp  1     32327 555129 198.69
## <none>                     522802 199.67
## - totAugRain   1     69527 592329 199.80
## - totJulyRain  1     83165 605967 200.18
## - aveAugTemp   1     94285 617087 200.49
## - DIJuly       1    231287 754089 203.90
## - TotalSnow    1    301739 824541 205.42
## - aveJUneTemp  1    331388 854190 206.02
## - DIAug        1    367663 890465 206.73
## - totJuneRain  1    452962 975764 208.28
## 
## Step:  AIC=197.67
## cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + totJuneRain + 
##     totJulyRain + totAugRain + DIJuly + DIAug + HDD + TotalSnow
## 
##               Df Sum of Sq    RSS    AIC
## - HDD          1     27034 549869 196.53
## - aveJulyTemp  1     32614 555449 196.70
## <none>                     522835 197.68
## - aveAugTemp   1     97295 620130 198.58
## - totJulyRain  1     98898 621732 198.62
## - totAugRain   1    100241 623076 198.66
## - TotalSnow    1    329088 851923 203.97
## - DIJuly       1    367653 890488 204.73
## - aveJUneTemp  1    369607 892442 204.76
## - DIAug        1    392195 915030 205.19
## - totJuneRain  1    456266 979101 206.34
## 
## Step:  AIC=196.53
## cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + totJuneRain + 
##     totJulyRain + totAugRain + DIJuly + DIAug + TotalSnow
## 
##               Df Sum of Sq     RSS    AIC
## <none>                      549869 196.53
## - totJulyRain  1     73186  623055 196.66
## - totAugRain   1    129142  679012 198.12
## - aveAugTemp   1    153126  702995 198.71
## - aveJulyTemp  1    205912  755782 199.94
## - DIJuly       1    340769  890638 202.73
## - DIAug        1    366514  916383 203.22
## - totJuneRain  1    447629  997498 204.66
## - aveJUneTemp  1    457061 1006930 204.82
## - TotalSnow    1    594298 1144167 206.99
## 
## Call:
## lm(formula = cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + 
##     totJuneRain + totJulyRain + totAugRain + DIJuly + DIAug + 
##     TotalSnow)
## 
## Coefficients:
## (Intercept)  aveJUneTemp  aveJulyTemp   aveAugTemp  totJuneRain  
##   -11939.13       208.49       -72.85        52.52      -171.76  
## totJulyRain   totAugRain       DIJuly        DIAug    TotalSnow  
##       44.02       -64.55      -241.50       276.32        21.62
anova(mymod, mymod2)
## Analysis of Variance Table
## 
## Model 1: cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + 
##     HDD + TotalSnow
## Model 2: cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + totJuneRain + 
##     totJulyRain + totAugRain + DIJune + DIJuly + DIAug + HDD + 
##     TotalSnow
##   Res.Df     RSS Df Sum of Sq      F Pr(>F)
## 1      9 1124802                           
## 2      5  522802  4    602000 1.4394 0.3444
fishL <- c(1565443, 1565708, 1492913,  1461112, 1492913, 1461112, 1467677, 1458013, 1478193, 1478193, 1492087, 1481758, 1518357, 1492460, 1418995, 1487547, 1423502)
mymod3 <- lm(cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + HDD + TotalSnow + fishL)
anova(mymod, mymod3)
## Analysis of Variance Table
## 
## Model 1: cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + 
##     HDD + TotalSnow
## Model 2: cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + 
##     HDD + TotalSnow + fishL
##   Res.Df     RSS Df Sum of Sq      F Pr(>F)
## 1      9 1124802                           
## 2      8  844216  1    280585 2.6589 0.1416
anova(mymod2, mymod3)
## Analysis of Variance Table
## 
## Model 1: cases ~ aveJUneTemp + aveJulyTemp + aveAugTemp + totJuneRain + 
##     totJulyRain + totAugRain + DIJune + DIJuly + DIAug + HDD + 
##     TotalSnow
## Model 2: cases ~ aveTotalTemp + totalRain + DIJune + DIJuly + DIAug + 
##     HDD + TotalSnow + fishL
##   Res.Df    RSS Df Sum of Sq      F Pr(>F)
## 1      5 522802                           
## 2      8 844216 -3   -321414 1.0247 0.4561
cor(cases, fishL)
## [1] -0.4753386