minor change to readme

README.md

@@ -61,10 +61,10 @@ Table D.1  | `ads_DiD_robust_missing_programs.R` |
 The `data` directory contains the following files: 
 
 
-File | Description
+File / Directory | Description
 ------ | ------ 
-`dd` | Day-by-day files with ad-level total news viewing by T/C group in 24 hour windows before and after air time
-`tuneout` | Day-by-day files with ad-level tuneout decisions
+`dd` | Directory with day-by-day files with ad-level total news viewing by T/C group in 24 hour windows before and after air time
+`tuneout` | Directory with day-by-day files with ad-level tuneout decisions
 `ads_dd_balance_all.RData` | Ad-level statistics (coefficient estimate and p-value) for demographic balance hypotheses
 `ads_dd_tuneout_all.RData` | Ad-level estimates of tune-out rate
 `all_dd_data.rds` | Ad-level total news viewing by T/C group in 24 hour windows before and after air time, used to construct DiD estimates (20 min window)