Class 1
Introduction
For this class, we’ll review code examples found in the Preface.
This assumes that you have already installed the rethinking package.
If you need help, be sure to remember the references in the Resources:
R Principles
## R code 0.1
print( "All models are wrong, but some are useful." )
## [1] "All models are wrong, but some are useful."
## R code 0.2
x <- 1:2
x <- x*10
x <- log(x)
x <- sum(x)
x <- exp(x)
x
## [1] 200
## R code 0.3
( log( 0.01^200 ) )
## [1] -Inf
( 200 * log(0.01) )
## [1] -921.034
## R code 0.4
# Load the data:
# car braking distances in feet paired with speeds in km/h
# see ?cars for details
data(cars)
# fit a linear regression of distance on speed
m <- lm( dist ~ speed , data=cars )
# estimated coefficients from the model
coef(m)
## (Intercept) speed
## -17.579095 3.932409
# plot residuals against speed
plot( resid(m) ~ speed , data=cars )
Package versions
sessionInfo()
## R version 4.1.1 (2021-08-10)
## Platform: aarch64-apple-darwin20 (64-bit)
## Running under: macOS Monterey 12.1
##
## Matrix products: default
## BLAS: /Library/Frameworks/R.framework/Versions/4.1-arm64/Resources/lib/libRblas.0.dylib
## LAPACK: /Library/Frameworks/R.framework/Versions/4.1-arm64/Resources/lib/libRlapack.dylib
##
## locale:
## [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
##
## attached base packages:
## [1] parallel stats graphics grDevices datasets utils methods
## [8] base
##
## other attached packages:
## [1] rethinking_2.21 cmdstanr_0.4.0.9001 rstan_2.21.3
## [4] ggplot2_3.3.5 StanHeaders_2.21.0-7
##
## loaded via a namespace (and not attached):
## [1] sass_0.4.0 jsonlite_1.7.2 bslib_0.3.1
## [4] RcppParallel_5.1.4 assertthat_0.2.1 posterior_1.1.0
## [7] distributional_0.2.2 highr_0.9 stats4_4.1.1
## [10] tensorA_0.36.2 renv_0.14.0 yaml_2.2.1
## [13] pillar_1.6.4 backports_1.4.1 lattice_0.20-44
## [16] glue_1.6.0 uuid_1.0-3 digest_0.6.29
## [19] checkmate_2.0.0 colorspace_2.0-2 htmltools_0.5.2
## [22] pkgconfig_2.0.3 bookdown_0.24 purrr_0.3.4
## [25] mvtnorm_1.1-3 scales_1.1.1 processx_3.5.2
## [28] tibble_3.1.6 generics_0.1.1 farver_2.1.0
## [31] ellipsis_0.3.2 withr_2.4.3 cli_3.1.0
## [34] mime_0.12 magrittr_2.0.1 crayon_1.4.2
## [37] evaluate_0.14 ps_1.6.0 fs_1.5.0
## [40] fansi_0.5.0 MASS_7.3-54 pkgbuild_1.3.1
## [43] blogdown_1.5 tools_4.1.1 loo_2.4.1
## [46] prettyunits_1.1.1 lifecycle_1.0.1 matrixStats_0.61.0
## [49] stringr_1.4.0 munsell_0.5.0 callr_3.7.0
## [52] compiler_4.1.1 jquerylib_0.1.4 rlang_0.4.12
## [55] grid_4.1.1 rstudioapi_0.13 base64enc_0.1-3
## [58] rmarkdown_2.11 xaringanExtra_0.5.5 gtable_0.3.0
## [61] codetools_0.2-18 inline_0.3.19 abind_1.4-5
## [64] DBI_1.1.1 R6_2.5.1 gridExtra_2.3
## [67] lubridate_1.8.0 knitr_1.36 dplyr_1.0.7
## [70] fastmap_1.1.0 utf8_1.2.2 downloadthis_0.2.1
## [73] bsplus_0.1.3 shape_1.4.6 stringi_1.7.6
## [76] Rcpp_1.0.7 vctrs_0.3.8 tidyselect_1.1.1
## [79] xfun_0.28 coda_0.19-4