Problem Set 1. Definitions
Relevant material will be covered by Aug 28. Problem set is due Sept 9 at 5pm.
Welcome to the first problem set! This homework will practice conceptual and notation ideas for descriptive and causal inference.
To complete the problem set, Download the .Rmd and complete the homework. Omit your name so we can have anonymous peer feedback. Compile to a PDF and submit the PDF on Canvas.
1. Practice with potential outcomes
Popeye says that eating spinach caused him to grow strong muscles. He claims that if he had not eaten spinach, he would not have grown strong muscles.
1.1 (7 points)
In Popeye’s claim, what is the treatment? You can either describe the treatment variable or explicitly write out the two options the treatment variable can take.
Answer. Your answer here
1.2 (7 points)
Using the mathematical notation we discussed in class, define the two potential outcomes to which Popeye is referring
Answer. Your answer here
1.3 (7 points)
In a sentence or two, say how the Fundamental Problem of Causal Inference applies to Popeye’s claim.
Answer. Your answer here
2. Taking 3900
You are wondering if taking STSCI 3900 will help you get a higher paying job. For each claim below, tell us whether the claim is causal or descriptive.
2.1 (5 points)
Last year, there was a survey of all Cornell students who have graduated in the past two years. The students who did take 3900 reported an average salary of 85,000 dollars and the students who did not take 3900 reported an average salary of 78,000 dollars.
Answer. Your answer here
2.2 (5 points)
A student who did not take the course took a job after graduation that paid 80,000. Had this student taken the course, they would have taken a job that paid 85,000.
Answer. Your answer here
Session info
The chunk below will record information about your R session, which is useful for debugging issues in homework assignments that contain code.
## R version 4.5.0 (2025-04-11)
## Platform: x86_64-pc-linux-gnu
## Running under: Ubuntu 22.04.5 LTS
##
## Matrix products: default
## BLAS: /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3
## LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblasp-r0.3.20.so; LAPACK version 3.10.0
##
## locale:
## [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
## [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
## [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
## [7] LC_PAPER=en_US.UTF-8 LC_NAME=C
## [9] LC_ADDRESS=C LC_TELEPHONE=C
## [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
##
## time zone: America/New_York
## tzcode source: system (glibc)
##
## attached base packages:
## [1] stats graphics grDevices utils datasets
## [6] methods base
##
## loaded via a namespace (and not attached):
## [1] digest_0.6.37 R6_2.6.1 bookdown_0.43
## [4] fastmap_1.2.0 xfun_0.52 glue_1.8.0
## [7] cachem_1.1.0 knitr_1.50 memoise_2.0.1
## [10] htmltools_0.5.8.1 rmarkdown_2.29 lifecycle_1.0.4
## [13] xml2_1.3.8 cli_3.6.5 downlit_0.4.4
## [16] vctrs_0.6.5 sass_0.4.10 withr_3.0.2
## [19] jquerylib_0.1.4 compiler_4.5.0 rstudioapi_0.17.1
## [22] tools_4.5.0 pillar_1.10.2 evaluate_1.0.4
## [25] bslib_0.9.0 yaml_2.3.10 fs_1.6.6
## [28] jsonlite_2.0.0 rlang_1.1.6