Update README.md

fa23-team/README.md

@@ -72,4 +72,24 @@ _Data should be rename to psam_p25_year.csv and put them in the same dirt._
 2. According to the PUMA information on https://www2.census.gov/geo/pdfs/reference/puma/2010_PUMA_Names.pdf and updated information on https://www2.census.gov/geo/pdfs/reference/puma/2010_PUMA_Names.pdf, create two dicts to store the area name and code of PUMA.
 3. Find the areas which in all years to analysis their average. Calculate the time difference between black and white of different areas across these years. Use (average * 2 * 5 * 50) / 60 to calculate the travel time difference between B&W each year.
 4. To draw Geography graph, I processed the result. Change all the areas names to zip codes, and then draw a graph using tableau. 
-5. Draw ring diagrams.
+5. Draw ring diagrams.
+
+6. ## Q1 and Q4
+
+### Overview
+This dataset is derived from the `American Community Survey (ACS) Public Use Microdata Sample (PUMS)` and contains information on the means of transportation to work for different racial groups over the time span of 2014 to 2021.
+
+### Dataset Source
+The data can be accessed from the U.S. Census Bureau at the following link: [ACS PUMS Data](https://www2.census.gov/programs-surveys/acs/data/pums/).
+
+### Time Span
+The dataset covers the period from 2014 to 2021.
+
+### Variables Description
+The following key variables are included in the dataset:
+
+- `JWTR/JWTRNS = 02`: This variable indicates that the means of transportation to work is by bus.
+- `RAC1P = 1`: This variable represents individuals who identify as White alone.
+- `RAC1P = 2`: This variable represents individuals who identify as Black or African American alone.
+
+### Data Preprocess