项目背景为提升低客单价用户Low AOV Users的下单转化意愿平台于 2024-05-01 在广州试点下调免运费门槛由原先“订单满 ¥99 包邮”调整为“订单满 ¥79 包邮”。该策略旨在降低用户心理门槛提升订单量但同时可能带来订单结构下沉AOV 下降与单均履约成本上升的风险。由于该政策属于区域性试点而非全量随机实验处理组广州与对照组其他城市在用户画像、消费习惯及物流成本结构上存在系统性差异简单对比无法识别政策的净效应。因此本项目采用 双重差分法DID在满足平行趋势假设的前提下剥离时间趋势与地区固定效应的影响从订单量、客单价AOV、订单结构、单均履约成本及净利润等维度系统评估免运费门槛下调的真实因果效应为后续全国推广或差异化包邮策略提供量化决策依据。分析思路-DID设计实验组-广州对照组深圳、佛山关键假设平行趋势政策前广州与深佛的下单行为趋势一致无同时干扰同期无其他针对广州的专项补贴或运力调整评估指标指标业务含义下单转化率下单 UV / 访问 UV客单价订单金额均值复购率当月下单 ≥2 次用户占比单均物流成本履约成本 / 订单数SQL取数城市*月份面板数据with user_event as ( -- 计算uv select city_name, date_format(event_date,%Y-%m) as ym, count(distinct user_id) as uv from ods_user_event where event_date between 2026-04-01 and 2026-05-31 and event_id visit group by city_name,date_format(event_date,%Y-%m) ), user_order as ( -- 订单统计 select city_name, date_format(order_date,%Y-%m) as ym, count(user_id) as order_users, count(distinct order_id) as order_cnt, sum(pay_amount) as gmv, sum(logistics_cost) as logistics_cost -- 物流成本 from dwd_order_detail where order_date between 2026-04-01 and 2026-05-31 and city_name in (广州,深圳,佛山) group by city_name,date_format(order_date,%Y-%m) ), user_repurchase as ( -- 复购统计 select city_name, ym, count(distinct case when user_order_cnt2 then user_id end) as repurchase_users from ( select user_id, city_name, date_format(order_date,%Y-%m) as ym, count(distinct order_id) as user_order_cnt from dwd_order_detail where order_date between 2026-04-01 and 2026-05-31 and city_name in (广州,深圳,佛山) group by user_id )x group by city_name,ym ) select city_name, ym, order_users/uv as conversion_rate, -- 下单转化率 gmv/order_cnt as avg_order_value, -- 客单价 repurchase_users/order_users as repurchase_rate, -- 复购率 logistics_cost/order_cnt as logistics_cost_per_order -- 每单物流成本 from user_event e left join user_order o on e.city_nameo.city_name and e.ymo.ym left join user_repurchase r on e.city_namer.city_name and e.ymr.ymcity_nameymconversion_rateavg_order_valuerepurchase_ratelogistics_cost_per_order广州2024-040.082112.30.1866.8广州2024-050.091108.50.2017.4深圳2024-040.081118.60.1926.5深圳2024-050.083117.90.1956.6佛山2024-040.079109.40.1786.3佛山2024-050.080109.10.1816.4PythonDID 回归 平行趋势检验import pandas as pd import statsmodels.formula.api as smf df pd.read_csv(city_month_metrics.csv) # 构造变量 df[treat] df[city_name].apply(lambda x: 1 if x 广州 else 0) df[post] df[ym].apply(lambda x: 1 if x 2024-05 else 0) df[did] df[treat] * df[post] # DID 回归 for y in [conversion_rate, avg_order_value, repurchase_rate, logistics_cost_per_order]: m smf.ols(f{y} ~ treat post did, datadf).fit(cov_typeHC1) print(f\n--- {y} ---) print(m.summary()) # 平行检验 # 构造相对月份 df[rel_month] df[ym].map({2024-04: -1, 2024-05: 0}) df pd.get_dummies(df, columns[rel_month], drop_firstTrue) # 政策前系数应不显著 model smf.ols( conversion_rate ~ treat*rel_month_-1 treat*rel_month_0, datadf ).fit(cov_typeHC1) print(model.summary())指标实验 Δ对照 ΔDID下单转化率0.0090.0010.008客单价-3.8-0.5-3.3​复购率1.50.31.2​物流成本0.60.10.5​项目结论下单转化率显著提升 0.8个百分点9.8%复购率提升 1.2个百分点6.4%客单价下降 ¥3.3用户更多购买低客单价商品单均物流成本上升 ¥0.57.7%业务解释降低包邮门槛有效降低了用户心理阻力尤其利好低客单价用户增量订单主要来自 “凑单型”小额订单物流成本上升幅度可控ROI 仍为正决策建议建议在珠三角其他城市推广 ¥79 包邮策略​建议配套措施对高物流成本区域动态定价引导用户参与“多件优惠”以提升客单价