【RTB论文笔记】

Bidding Strategies

CTR/CVR Estimation

2017

Attribution Modeling Increases Efficiency of Bidding in Display Advertising by Eustache Diemert et al. ADKDD 2017.

归属模型提高展示广告竞价效率

数据集:Criteo、Facebook真实场景

offline数据结:http://research.criteo.com/criteo-attribution-modeling-bidding-dataset/

Abstra

ct以往算法将转化率预估和转化行为归因于哪次广告行为(展示或者点击)分开研究,是两个独立的问题,但是作者发现,归因模型有助于提高竞价的效果,因此将转化行为归因于哪次广告活动加入竞价策略中,提高竞价效率。

Introduction

衡量展示广告效果基于广告展示带来的价值,目前主要的两种方式:CPC,CPA(cost per action),工业界中归因转化的标准是:归因于转化之前30天之内最后一次点击行为。

对于广告引擎和平台来说,目前最先进的出价策略是:Expected Value Bidder (EVB),也就是根据展示机会的预期价值来出价。预期价值是广告主payment*预测的转化率

在博弈论和经济学领域,转化归因已有深入研究,已经有一些机制被提出去较好地衡量广告主的payment,尤其是在多个广告点击或者转化行为同时发生或多个渠道同时存在的情况下。

考虑一个广告行为序列,合理的出价方式是后面的展示行为都应该比第一次展示的价值低,因为第二次点击行为能够导致转化的可能性不高。在之前的EVB策略中,是没有这方面考虑的,因为它既不能跟踪也不能预测归因转化率,所以为了改进实时竞价策略,我们建议利用一个归因模型来修改投标策略。

Model

把转化归因于最后一次点击行为适用于CPM结算方式,但不是很适合CPCorCPA方式。

从数据中学习归因关系,假设广告投放平台可以访问其广告主客户的转化归属标签,(该广告主通过其他广告投放平台的转化归主标签不可访问)

将归属关系表达成间隔时间的负指数函数,竞价策略为CPA*归属概率。

Data description

This dataset represents a sample of 30 days of Criteo live traffic data. Each line corresponds to one impression (a banner) that was displayed to a user. For each banner we have detailed information about the context, if it was clicked, if it led to a conversion and if it led to a conversion that was attributed to Criteo or not. Data has been sub-sampled and anonymized so as not to disclose proprietary elements.

Here is a detailed description of the fields (they are tab-separated in the file):

  • timestamp: timestamp of the impression (starting from 0 for the first impression). The dataset is sorted according to timestamp.
  • uid a unique user identifier
  • campaign a unique identifier for the campaign
  • conversion 1 if there was a conversion in the 30 days after the impression (independently of whether this impression was last click or not)
  • conversion_timestamp the timestamp of the conversion or -1 if no conversion was observed
  • conversion_id a unique identifier for each conversion (so that timelines can be reconstructed if needed). -1 if there was no conversion
  • attribution 1 if the conversion was attributed to Criteo, 0 otherwise
  • click 1 if the impression was clicked, 0 otherwise
  • click_pos the position of the click before a conversion (0 for first-click)
  • click_nb number of clicks. More than 1 if there was several clicks before a conversion
  • cost the price paid by Criteo for this display (disclaimer: not the real price, only a transformed version of it)
  • cpo the cost-per-order in case of attributed conversion (disclaimer: not the real price, only a transformed version of it)
  • time_since_last_click the time since the last click (in s) for the given impression
  • cat[1-9] contextual features associated to the display. Can be used to learn the click/conversion models. We do not disclose the meaning of these features but it is not relevant for this study. Each column is a categorical variable. In the experiments, they are mapped to a fixed dimensionality space using the Hashing Trick (see paper for reference).

Criteo Data

  • timestamp: 时间戳
  • uid 用户id
  • campaign 推广计划id
  • conversion 转化
  • conversion_timestamp 转化时间
  • conversion_id 转化id
  • attribution 转化归属关系
  • click 点击
  • click_pos 点击次序
  • click_nb 点击数量
  • cost 成本价格,Criteo赢得展示所支付的费用
  • cpo the cost-per-order in case of attributed conversion (disclaimer: not the real price, only a transformed version of it)
  • time_since_last_click 最后一次点击时间到转化的间隔时间
  • cat[1-9] 上下文特征,hash过。

Managing Risk of Bidding in Display Advertising by Haifeng Zhang et al. WSDM 2017.

数据集:iPinyou

Abstract

广告主投放广告就像是金融投资一样,也具有风险,本文中我们明确地给出用户点击率估计的模型和竞价竞争模型来控制风险,我们从金融学引入一个idea,形成两个风险感知的竞价策略,惩罚具有风险的广告展示机会,更多地关注高收益、低风险的广告。

Introduction

提到了一些DSP平台:ipinyou,YOYI,Fikisu,广告市场的交易量已经超过了金融市场。

竞价策略依赖于点击率或者转化率的预估,但是点击率预估的不准确可能会导致价值估计的严重不准确,会带来巨大利润估计风险。本文中我们脱离传统的ctr预估,而是对每一个广告展示机会潜在的风险进行建模。

Real-Time Bidding rules of thumb: analytically optimizing the programmatic buying of ad-inventory by Joaquin Fernandez-Tapia. SSRN 2015.

优化目标:一定预算约束下,实现广告位采买最大化

比较关注的三种技术:

  1. 静态宏观变量对广告活动的运作十分重要
  2. 针对不同广告位的竞价优化
  3. 预算步进优化

Introduction

  1. 工业背景:

  2. 不同规模的模型:

    一次广告竞价是微观的过程,但是衡量其表现却是宏观过程,比如衡量其一个月、一天的收益

  3. 假设

  4. 优化问题

  5. 本文提纲和贡献