BigQuery ML ARIMA Model on GA4 purchase data

bqml_ga4.sql

CREATE OR REPLACE MODEL `your-project.arima_test.purchase_forecast`
OPTIONS(model_type='ARIMA_PLUS', time_series_timestamp_col='date', time_series_data_col='daily_purchases')
AS
SELECT 
    PARSE_DATE('%Y%m%d', event_date) as date, 
    COUNTIF(event_name = 'purchase') as daily_purchases
FROM 
    `bigquery-public-data.ga4_obfuscated_sample_ecommerce.events_*`
WHERE 
    _TABLE_SUFFIX BETWEEN '20201101' AND '20211231'
GROUP BY 
    date
order by date;

SELECT 
    *
FROM 
    ML.FORECAST(MODEL `your-project.arima_test.purchase_forecast`, STRUCT(90 AS horizon));