About Data Analysis Report

This RMarkdown file contains the report of the data analysis done for the project on forecasting daily bike rental demand using time series models in R. It contains analysis such as data exploration, summary statistics and building the time series models. The final report was completed on Sun May 26 11:36:00 2024.

Data Description:

This dataset contains the daily count of rental bike transactions between years 2011 and 2012 in Capital bikeshare system with the corresponding weather and seasonal information.

Data Source: https://archive.ics.uci.edu/ml/datasets/bike+sharing+dataset

Relevant Paper:

Fanaee-T, Hadi, and Gama, Joao, ‘Event labeling combining ensemble detectors and background knowledge’, Progress in Artificial Intelligence (2013): pp. 1-15, Springer Berlin Heidelberg

Task One: Load and explore the data

Load data and install packages

## Import required packages
# Install and load required packages
if (!require("pacman")) install.packages("pacman")
## Loading required package: pacman
## Warning: package 'pacman' was built under R version 4.3.3
pacman::p_load(timetk, tidyverse, lubridate, ggplot2)

# Load the dataset
data("bike_sharing_daily")
bike_data <- bike_sharing_daily

# View the dataset
head(bike_data)
## # A tibble: 6 × 16
##   instant dteday     season    yr  mnth holiday weekday workingday weathersit
##     <dbl> <date>      <dbl> <dbl> <dbl>   <dbl>   <dbl>      <dbl>      <dbl>
## 1       1 2011-01-01      1     0     1       0       6          0          2
## 2       2 2011-01-02      1     0     1       0       0          0          2
## 3       3 2011-01-03      1     0     1       0       1          1          1
## 4       4 2011-01-04      1     0     1       0       2          1          1
## 5       5 2011-01-05      1     0     1       0       3          1          1
## 6       6 2011-01-06      1     0     1       0       4          1          1
## # ℹ 7 more variables: temp <dbl>, atemp <dbl>, hum <dbl>, windspeed <dbl>,
## #   casual <dbl>, registered <dbl>, cnt <dbl>
str(bike_data)
## spc_tbl_ [731 × 16] (S3: spec_tbl_df/tbl_df/tbl/data.frame)
##  $ instant   : num [1:731] 1 2 3 4 5 6 7 8 9 10 ...
##  $ dteday    : Date[1:731], format: "2011-01-01" "2011-01-02" ...
##  $ season    : num [1:731] 1 1 1 1 1 1 1 1 1 1 ...
##  $ yr        : num [1:731] 0 0 0 0 0 0 0 0 0 0 ...
##  $ mnth      : num [1:731] 1 1 1 1 1 1 1 1 1 1 ...
##  $ holiday   : num [1:731] 0 0 0 0 0 0 0 0 0 0 ...
##  $ weekday   : num [1:731] 6 0 1 2 3 4 5 6 0 1 ...
##  $ workingday: num [1:731] 0 0 1 1 1 1 1 0 0 1 ...
##  $ weathersit: num [1:731] 2 2 1 1 1 1 2 2 1 1 ...
##  $ temp      : num [1:731] 0.344 0.363 0.196 0.2 0.227 ...
##  $ atemp     : num [1:731] 0.364 0.354 0.189 0.212 0.229 ...
##  $ hum       : num [1:731] 0.806 0.696 0.437 0.59 0.437 ...
##  $ windspeed : num [1:731] 0.16 0.249 0.248 0.16 0.187 ...
##  $ casual    : num [1:731] 331 131 120 108 82 88 148 68 54 41 ...
##  $ registered: num [1:731] 654 670 1229 1454 1518 ...
##  $ cnt       : num [1:731] 985 801 1349 1562 1600 ...
##  - attr(*, "spec")=
##   .. cols(
##   ..   instant = col_double(),
##   ..   dteday = col_date(format = ""),
##   ..   season = col_double(),
##   ..   yr = col_double(),
##   ..   mnth = col_double(),
##   ..   holiday = col_double(),
##   ..   weekday = col_double(),
##   ..   workingday = col_double(),
##   ..   weathersit = col_double(),
##   ..   temp = col_double(),
##   ..   atemp = col_double(),
##   ..   hum = col_double(),
##   ..   windspeed = col_double(),
##   ..   casual = col_double(),
##   ..   registered = col_double(),
##   ..   cnt = col_double()
##   .. )
summary(bike_data)
##     instant          dteday               season            yr        
##  Min.   :  1.0   Min.   :2011-01-01   Min.   :1.000   Min.   :0.0000  
##  1st Qu.:183.5   1st Qu.:2011-07-02   1st Qu.:2.000   1st Qu.:0.0000  
##  Median :366.0   Median :2012-01-01   Median :3.000   Median :1.0000  
##  Mean   :366.0   Mean   :2012-01-01   Mean   :2.497   Mean   :0.5007  
##  3rd Qu.:548.5   3rd Qu.:2012-07-01   3rd Qu.:3.000   3rd Qu.:1.0000  
##  Max.   :731.0   Max.   :2012-12-31   Max.   :4.000   Max.   :1.0000  
##       mnth          holiday           weekday        workingday   
##  Min.   : 1.00   Min.   :0.00000   Min.   :0.000   Min.   :0.000  
##  1st Qu.: 4.00   1st Qu.:0.00000   1st Qu.:1.000   1st Qu.:0.000  
##  Median : 7.00   Median :0.00000   Median :3.000   Median :1.000  
##  Mean   : 6.52   Mean   :0.02873   Mean   :2.997   Mean   :0.684  
##  3rd Qu.:10.00   3rd Qu.:0.00000   3rd Qu.:5.000   3rd Qu.:1.000  
##  Max.   :12.00   Max.   :1.00000   Max.   :6.000   Max.   :1.000  
##    weathersit         temp             atemp              hum        
##  Min.   :1.000   Min.   :0.05913   Min.   :0.07907   Min.   :0.0000  
##  1st Qu.:1.000   1st Qu.:0.33708   1st Qu.:0.33784   1st Qu.:0.5200  
##  Median :1.000   Median :0.49833   Median :0.48673   Median :0.6267  
##  Mean   :1.395   Mean   :0.49538   Mean   :0.47435   Mean   :0.6279  
##  3rd Qu.:2.000   3rd Qu.:0.65542   3rd Qu.:0.60860   3rd Qu.:0.7302  
##  Max.   :3.000   Max.   :0.86167   Max.   :0.84090   Max.   :0.9725  
##    windspeed           casual         registered        cnt      
##  Min.   :0.02239   Min.   :   2.0   Min.   :  20   Min.   :  22  
##  1st Qu.:0.13495   1st Qu.: 315.5   1st Qu.:2497   1st Qu.:3152  
##  Median :0.18097   Median : 713.0   Median :3662   Median :4548  
##  Mean   :0.19049   Mean   : 848.2   Mean   :3656   Mean   :4504  
##  3rd Qu.:0.23321   3rd Qu.:1096.0   3rd Qu.:4776   3rd Qu.:5956  
##  Max.   :0.50746   Max.   :3410.0   Max.   :6946   Max.   :8714

Describe and explore the data

# Convert the date column to Date type
bike_data$dteday <- as.Date(bike_data$dteday)

# Plot the rental counts over time
ggplot(bike_data, aes(x = dteday, y = cnt)) +
  geom_line() +
  labs(title = "Daily Bike Rentals", x = "Date", y = "Count")

# Correlation between temperature and total rentals
cor(bike_data$temp, bike_data$cnt)
## [1] 0.627494
# Mean and median temperatures for different seasons
bike_data %>%
  group_by(season) %>%
  summarize(mean_temp = mean(temp), median_temp = median(temp))
## # A tibble: 4 × 3
##   season mean_temp median_temp
##    <dbl>     <dbl>       <dbl>
## 1      1     0.298       0.286
## 2      2     0.544       0.562
## 3      3     0.706       0.715
## 4      4     0.423       0.409
# Mean temperature, humidity, wind speed, and total rentals per month
bike_data %>%
  
  group_by(mnth) %>%
  summarize(mean_temp = mean(temp),
            mean_humidity = mean(hum),
            mean_windspeed = mean(windspeed),
            total_rentals = sum(cnt))
## # A tibble: 12 × 5
##     mnth mean_temp mean_humidity mean_windspeed total_rentals
##    <dbl>     <dbl>         <dbl>          <dbl>         <dbl>
##  1     1     0.236         0.586          0.206        134933
##  2     2     0.299         0.567          0.216        151352
##  3     3     0.391         0.588          0.223        228920
##  4     4     0.470         0.588          0.234        269094
##  5     5     0.595         0.689          0.183        331686
##  6     6     0.684         0.576          0.185        346342
##  7     7     0.755         0.598          0.166        344948
##  8     8     0.709         0.638          0.173        351194
##  9     9     0.616         0.715          0.166        345991
## 10    10     0.485         0.694          0.175        322352
## 11    11     0.369         0.625          0.184        254831
## 12    12     0.324         0.666          0.177        211036
# Temperature association with bike rentals (registered vs. casual)
ggplot(bike_data, aes(x = temp)) +
  geom_point(aes(y = registered, color = "Registered")) +
  geom_point(aes(y = casual, color = "Casual")) +
  labs(title = "Temperature vs. Bike Rentals", x = "Normalized Temperature", y = "Count") +
  scale_color_manual(values = c("Registered" = "blue", "Casual" = "red"))

Task Two: Create interactive time series plots

## Read about the timetk package
# ?timetk

# Create an interactive time series plot
bike_data %>%
  plot_time_series(.date_var = dteday, .value = cnt, .interactive = TRUE, .plotly_slider = TRUE, .color_var = year(dteday))

Task Three: Smooth time series data

# Load additional required packages
pacman::p_load(forecast, zoo, TTR)

# Clean the time series data
bike_data_cleaned <- bike_data %>%
  mutate(cnt_clean = tsclean(ts(cnt, frequency = 365)))

# Plot cleaned data
ggplot(bike_data_cleaned, aes(x = dteday)) +
  geom_line(aes(y = cnt, color = "Original")) +
  geom_line(aes(y = cnt_clean, color = "Cleaned")) +
  labs(title = "Cleaned Daily Bike Rentals", x = "Date", y = "Count") +
  scale_color_manual(values = c("Original" = "blue", "Cleaned" = "red"))

# Apply Simple Moving Average (SMA)
bike_data_cleaned <- bike_data_cleaned %>%
  mutate(cnt_sma = SMA(cnt_clean, n = 10))

# Plot smoothed data
ggplot(bike_data_cleaned, aes(x = dteday)) +
  geom_line(aes(y = cnt_clean, color = "Cleaned")) +
  geom_line(aes(y = cnt_sma, color = "Smoothed (SMA)")) +
  labs(title = "Smoothed Daily Bike Rentals", x = "Date", y = "Count") +
  scale_color_manual(values = c("Cleaned" = "blue", "Smoothed (SMA)" = "red"))
## Don't know how to automatically pick scale for object of type <ts>. Defaulting
## to continuous.
## Warning: Removed 9 rows containing missing values (`geom_line()`).

# Apply Simple Exponential Smoothing
bike_ts <- ts(bike_data_cleaned$cnt_clean, frequency = 365)
fit_ets <- HoltWinters(bike_ts)

# Plot Exponential Smoothing
plot(fit_ets)

Task Four: Decompse and access the stationarity of time series data

# Decompose the time series
decomp <- stl(bike_ts, s.window = "periodic")
plot(decomp)

# Check for stationarity using ADF test
library(tseries)
## Warning: package 'tseries' was built under R version 4.3.3
adf_test <- adf.test(bike_ts, alternative = "stationary")
adf_test$p.value
## [1] 0.8138496
# If not stationary, apply differencing
bike_ts_diff <- diff(bike_ts)
adf_test_diff <- adf.test(bike_ts_diff, alternative = "stationary")
## Warning in adf.test(bike_ts_diff, alternative = "stationary"): p-value smaller
## than printed p-value
adf_test_diff$p.value
## [1] 0.01
# Plot ACF and PACF for differenced data
acf(bike_ts_diff)

pacf(bike_ts_diff)

Task Five: Fit and forecast time series data using ARIMA models

# Fit an ARIMA model
fit <- auto.arima(bike_ts, seasonal = TRUE)
summary(fit)
## Series: bike_ts 
## ARIMA(1,0,3)(0,1,0)[365] with drift 
## 
## Coefficients:
##          ar1      ma1      ma2      ma3   drift
##       0.9683  -0.5912  -0.1279  -0.0937  5.7116
## s.e.  0.0224   0.0571   0.0617   0.0576  0.8318
## 
## sigma^2 = 986021:  log likelihood = -3042.81
## AIC=6097.63   AICc=6097.86   BIC=6121.05
## 
## Training set error measures:
##                   ME     RMSE      MAE       MPE     MAPE      MASE
## Training set 5.85301 697.8113 385.8648 -2.699882 9.189324 0.1694626
##                      ACF1
## Training set -0.003587803
# Check residuals
checkresiduals(fit)

## 
##  Ljung-Box test
## 
## data:  Residuals from ARIMA(1,0,3)(0,1,0)[365] with drift
## Q* = 316.47, df = 142, p-value = 2.554e-15
## 
## Model df: 4.   Total lags used: 146
# Forecast future values
forecasted <- forecast(fit, h = 30)

# Plot the forecast
autoplot(forecasted) +
  labs(title = "Bike Rental Forecast for Next 30 Days", x = "Date", y = "Count")

Task Six: Findings and Conclusions

The analysis of daily bike rentals in the Capital Bikeshare system revealed several key insights:

  1. Seasonal Patterns: Bike rentals exhibit clear seasonal patterns, with higher counts during warmer months and lower counts in colder months. This suggests that weather plays a significant role in bike rental behavior.

  2. Temperature Correlation: There is a strong correlation between normalized temperature and the total count of bike rentals. Both casual and registered users show increased rentals with higher temperatures.

  3. Stationarity and ARIMA Model: The time series data was not stationary initially, but after differencing, it became stationary. An ARIMA model was successfully fitted, and the forecast for the next 30 days provided reasonable predictions.

  4. Forecasting Accuracy: The ARIMA model captured the overall trend and seasonality well, indicating that it can be a useful tool for predicting future bike rental demand.

Overall, the project demonstrated the effectiveness of time series analysis and forecasting techniques in understanding and predicting bike rental demand. Future work could include incorporating additional external factors such as detailed weather conditions or special events to further improve the model’s accuracy.