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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Entire Cost Enhanced Multi-Task Model for Online-to-Ofline Conversion Rate Prediction</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Yingyi Zhang</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Xianneng Li</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yahe Yu</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jian Tang</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Huanfang Deng</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Junya Lu</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yeyin Zhang</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Qiancheng Jiang</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yunsen Xian</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Liqian Yu</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>: Workshop on Deep Learning for Search</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Recommen- dation</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>co-located with the</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>st ACM International Conference on Information</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Knowledge Management (CIKM)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>October</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Atlanta</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>xianneng@dlut.edu.cn (X. Li)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>yaheyu@dlut.edu.cn (Y. Yu)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>tangjian</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>@meituan.com (J. Tang)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>denghuanfang@meituan.com (H. Deng)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>lujunya@meituan.com (J. Lu)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>zhangyeyin@meituan.com (Y. Zhang)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>jiangqiancheng@meituan.com (Q. Jiang)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>xianyunsen@meituan.com (Y. Xian)</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>yuliqian@meituan.com (L. Yu)</string-name>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Dalian University of Technology</institution>
          ,
          <addr-line>Dalian, 116024</addr-line>
          ,
          <country country="CN">China</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Meituan</institution>
          ,
          <addr-line>Beijing, 100102</addr-line>
          ,
          <country country="CN">China</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Predicting users' conversion rate (CVR) is essentially important for ranking systems in industrial Online-to-Ofline (O2O) applications. Numerous eforts have been made in CVR modeling to achieve state-of-the-art performance. However, existing methods mainly focus on the Business-to-Customer (B2C) scenario, which makes implementations to O2O meet with mixed success. This can be revealed via several scenario-specific challenges. For example, O2O users in diferent locations generally encounter diferent candidates of surrounding stores. This leads to users' behavioral regularity becoming essentially prominent. Besides, O2O users' conversion includes a two-stage cost, i.e., online order cost and ofline transportation cost. This inspires that users' location sensitivity deserves additional attention compared with conventional scenarios. Motivated by these characteristics, we propose a novel CVR prediction method for the O2O scenario, named Entire Cost enhanced Multi-task Model (ECMM): i) users' historical behavior sequences across diferent locations are modeled to capture the users' preference of behavioral regularity; ii) both online order cost and ofline transportation cost are modeled to predict the users' aggregated preference for conversion. By designing two novel attention mechanisms, i.e., convert attention and sliding window attention, ECMM can be trained end-to-end to appropriately fit O2O characteristics. Extensive experiments have been carried out under a real-world industrial O2O platform Meituan. Both ofline and rigorous online A/B tests under the billion-level data scale demonstrate the superiority of the proposed ECMM over the highly optimized state-of-the-art baselines.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Online-to-Ofline</kwd>
        <kwd>Multi-Task Learning</kwd>
        <kwd>Conversion Rate Prediction</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>Offline stores that user interacted historical y
• ECMM elongates the observation dimensions by
learning users’ online conversion preferences
from historical behavior sequences. A new
mechanism named convert attention is proposed to
learn the user’s behavior regularity from the
global and local perspectives of online order cost.
• To the best of our knowledge, ECMM is the first
method for CVR modeling from the perspective
of ofline transportation cost. We propose a new
mechanism named sliding window attention to
dynamically learn users’ preference of ofline
transportation.
• ECMM is testified under a real-world industrial
O2O platform, where extensive experiments are
carried out. Both ofline and rigorous online A/B
tests under the billion-level data scale
demonstrate the significant superiority of ECMM over
the state-of-the-art baselines.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related Work</title>
      <p>
        [
        <xref ref-type="bibr" rid="ref1 ref17">10, 11, 12, 13, 14, 15</xref>
        ] and some method solving domain respectively. We note that the first three terms are the
specifically problem are proposed [ 16, 17, 18, 19]. How- information widely used in conventional CVR modeling,
ever, where the intrinsic characteristics of O2O, i.e., on- while ℎ and ℎ are two newly considered ones to assist
line behavioral regularity and ofline transportation reg- in the modeling of behavioral and transportation
reguularity, are rarely considered. larities. Moreover, the user’s click and order sequences
      </p>
      <p>
        One possible strategy to improve learning users’ online in ECMM are used from the online-ofline cost
perspecbehavioral regularity and ofline transportation regular- tive, i.e., online order cost and ofline transportation cost,
ity is to consider user statistical features i.e. user’s aver- which are essentially diferent from that of conventional
age online order cost and user’s average ofline distance CTR prediction methods of modeling user’s multiple
infeatures. However, in O2O scenarios, the spatiotemporal terests [
        <xref ref-type="bibr" rid="ref13 ref38">20, 21, 22, 23, 24, 25</xref>
        ]. As a novel CVR prediction
nature is inseparable, and using this strategy will lose method for the O2O scenario, the contributions of ECMM
time-series information when characterizing user pref- are threefold:
erences. Therefore, sequence representation techniques
are also taken into account as shown in Figure 1.
Inspired by the success within deep learning, recent CVR
prediction model has evolved from traditional approaches
to deep approaches. Traditional method used logistic
( = 1|) regression [26, 27] and GBDT [28] for modeling CVR
( = 1| = 1, ) = ( = 1|) , (1) problem with feature interactions. However, nonlinear
relationships of features are not considered in these
modwhere  is (, , , ℎ, ℎ),  is the user,  denotes the els. Modern deep learning based method transforms CVR
store, and  represents the current context, such as the problem into a multi-task problem [
        <xref ref-type="bibr" rid="ref1 ref17">10, 11, 12</xref>
        ]. ESMM
current time, city, day of the week, and other informa- [
        <xref ref-type="bibr" rid="ref1 ref17">10</xref>
        ] make use of users sequential actions, "impression
tion that is independent of user and store. ℎ and ℎ are → click → pay", to solve sample selection bias and data
the user’s historical click sequence and order sequence, sparsity problem over the entire space by simultaneous
modeling of CTR and CTCVR tasks. ESM2 [11] method and context features, the entire cost module contain both
extends users sequential actions to a more general situa- the user’s click and order sequence to capture the user’s
tion, "impression → click → D(O)Action →pay", which historical cost preference, and the cost combination
modsimultaneous models CVR with CTR, CTAVR and CTCVR ule for combining online-to-ofline cost to predict CTR
tasks. HM3 [12] form "impression → click → D(O)Mi and CVR. With this network, the model can capture the
→ D(O)Ma → pay" perspective models CVR with CTR, user’s online behavioral and ofline transportation
regD-Mi, D-Ma and CTCVR tasks. ularities, which are hidden in users’ historical behavior
      </p>
      <p>However, all these methods are based on B2C e- sequences. The details of each module are described as
commerce platforms which makes implementations to follows.</p>
      <p>
        O2O platforms meet with mixed success. Users have
unique sequential actions in O2O, which can be repre- 3.1. Motivation
sented as "impression→click→online order→ofline
consumption". Such situations require CVR model to con- As discussed in the previous section, users’ online
behavsider not only user online behavioral regularity, but also ioral and ofline transportation regularities are
indispensofline transportation regularity. able for O2O recommendation [
        <xref ref-type="bibr" rid="ref38 ref9">9, 2, 20, 21</xref>
        ]. However,
how to define their relationship with users’ behavior
se2.2. User Behavior Sequence quence as well as embody both online and ofline cost
into a unified framework for CVR prediction remains
      </p>
      <p>Representation unexplored.</p>
      <p>
        In the past decade, user behavior sequence representation For one thing, we propose a novel CVR prediction
have received much attention and achieved remarkable method from the perspective of user historical behavior.
efectiveness. Many well designed recommender meth- We proposed convert attention to extract the local and
ods have been proposed and brought huge commercial global preference of users’ online-to-ofline behaviors
revenues for companies and advertisers. In this mod- from both depth and breadth perspectives. From a
loels, users’ history behaviors are transformed into low- cal view, an order placed by a user is afected by clicks.
dimension vectors after embedding to represent users’ We design the local impact of a click on a order from
interest and other character. DIN [
        <xref ref-type="bibr" rid="ref38">20</xref>
        ] employs the atten- the store perspective. From a global perspective, users’
tion mechanism to activate historical behaviors locally overall order sequence receives the impression of click
which capture user diversity interest to the given target sequence in terms of id, price, and relative distance. For
item. DIEN [21] further proposes an auxiliary loss and another, to model users’ transportation cost, we capture
attention mechanism with GRU to capture the dynamic the information of the distance sequence implied in users’
evolution of users interest. DFN [29] jointly consider preference for ofline cost in the O2O scenario, to assist
explicit/implicit and positive/negative feedbacks to learn the model in learning users’ conversion preference in
user unbiased preferences. Moreover, inspired by the suc- the ofline stage. Each store of a user’s historical click
cess of the self-attention architecture [30], Transformer and order has distance features which means the ofline
is introduced in for session CTR prediction [31]. MIND transportation cost. Then we use sliding window
atten[32] and DMIN [33] model multi-interest by multiple tion method to calculate the user dynamic preference for
vectors with dynamic routing mechanism and capsule ofline cost during diferent timestamps.
network.
      </p>
      <p>Although all these user behavior sequence representa- 3.2. Base Module
tion methods have brought a huge boost to the business
from the perspective of user interest, there are still
opportunities for improvement in modeling user behavior
sequences from other perspectives. Cost sensitivity [34]
is an indispensable aspect of user modeling, and users of
e-commerce often have certain restrictions on payment
costs which makes it possible to further improve the user
behavior sequence modeling from the perspective of cost.</p>
      <sec id="sec-2-1">
        <title>The base module is used to aggregate the basic features.</title>
        <p>
          Refer to [
          <xref ref-type="bibr" rid="ref1 ref17">10, 11, 12</xref>
          ], the embedding and MLP (multiple
layer perception) structures are used in the base
module. The user, store, and contextual features ( ∈ R ,
 ∈ R , and  ∈ R ) are the inputs of the base module,
which are mapped into a d-dimensional space via
embedding operations. MLP are used to learn the aggregated
vector  of basic features, with ELU [35] as the activation
function:
 =  (  ((, , ))).
(2)
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. The Proposed Approach</title>
      <sec id="sec-3-1">
        <title>In this section, we introduce the proposed ECMM model. As shown in Figure 2, it consists of three modules, which are base module includes the online user, the ofline store</title>
        <p>CTCVR
Share net feature concat
CVR
CVR network</p>
        <sec id="sec-3-1-1">
          <title>3.3. Entire Cost Module</title>
          <p>restriction. The sparse attention takes the embedding
of the user’s current context feature, click and order
sequences as input, and then get the most important user
click and order behavior in the current context. The
sparse attention [36] is defined as follows:
Diferent from B2C purchase, O2O scenario generally
considers surrounding stores of a user’s location. Limited
candidates actually reduce the possibility of matching
with users’ preference. Thus, it is critical to accurately
capture the user’s behavioral regularity from historical 
behaviors. Meanwhile, O2O users need to consider two- (, ,  ) =  (( √
stage costs for decision making, i.e., online order cost
and ofline transportation cost, both of which should be
considered. Entire cost module is designed to solve the
above problems and is the most important part of the
ECMM model. It contains two parts: online cost feature
module and ofline cost feature module.</p>
          <p>Online Cost Feature Module. Each store that in
the user’s click or order sequence has side-information
features of id , distance  and price  that
represent the user cost that he decide to click/order an ofline
store in the online platform. Then we have embedding
of the i-th store in user historical behavior,
(7)
where the  operation takes the top  pieces of
historical information most relevant to the current context.</p>
          <p>Through the sparse attention, we can get the updated
embeddings of user’s click and order sequences:</p>
          <p>(9)
where  means converts context features as query
vector, {,  } denotes converts the user click sequence
as key and value vectors and {,  } as well.
ℎ = (, , ), ℎ ∈ R3. (3) In order to better capture the impact of the user click
sequence  on the order sequence  from the retrieved
ℎ = (, , ), ℎ ∈ R3. (4) click and order aggregation information, we propose a
Thus, the user’s historical click and order behavior se- convert attention mechanism to capture these impacts
quences, i.e.,  and , can be represented as follows: from both local and global perspectives.
From a local perspective, the preference of the user’s
 = (ℎ1 , ℎ2 , ..., ℎ),  ∈ R× 3, (5) conversion to store ℎ, ∈  can be characterized by
the clicked store ℎ, ∈  related to where the order
 = (ℎ1, ℎ2, ..., ℎ),  ∈ R× 3, (6) was placed:
 = (, ,  ),  ∈ R× 3,
 = (, ,  ),  ∈ R× 3,</p>
          <p>(8)
)) ,
where  denotes the length of user’s click and order
sequences.</p>
          <p>After embedding, the sparse attention is used to
capture the user’s historical preference under contextual
  = (W ×
ℎ,) ⊗ (  ×
ℎ, ) ,</p>
          <p>(10)
, = Σ =1

(  ) ×
ℎ, + ℎ, , ℎ, ∈ R3, (11)</p>
          <p>Σ =1(  )
 = (,),  = (,),  = (,),
 ∈ R× .</p>
          <p>(12)</p>
          <p>For each dimension, we calculate the impact of the
user’s clicked sequence on the user’s order sequence
from a global perspective:
  = (  ×
,) ⊗ (  ×</p>
          <p>, ) , (13)
(  )
, = Σ  Σ (  ) , + , ,
, =  ,:+, , ∈ R× ,  ∈ {, }, (19)
, =  (
,
√
), , ∈ R× ,  ∈ {, },</p>
          <p>(20)
  = Σ =1,,,   ∈ R× ,  ∈ {, },</p>
          <p>(21)
where  ∈ N denotes our window length, ,
denotes the subsequence in -th window,   denotes
the user ofline preference of the window length
dimension matrix, and  =  ( ) denotes the
user ofline preference vector.
where ,  ∈ R3× 3 is trainable parameters.   We propose a sliding window attention mechanism that
represents the correlation between clicked store  and or- uses fixed-length windows to characterize the user’s
prefder store . , means to use the aggregation of clicked erence for transportation cost in diferent periods,
bestores information to obtain the local conversion prefer- cause the user’s preference for transportation cost varies
ence to update the order store information. Here, we use in diferent periods. Note the mechanism has generation
the residual design to retain the original information of for not only O2O platform users but also for other
scethe order store. nario which need to capture user dynamic preference</p>
          <p>From a global perspective, the user’s preferences for during diferent period.
diferent dimensions (i.e., store’s id, price, distance) of Each ofline store has a distance feature  ∈ R
order stores are afected by the relevant information of with respect to the current store, we match this feature
the clicked store. Hence, we separate the submatrix from with the user’s historical distance sequence:
the click and order sequences:
Datasets. We selected 30 days exposure logs from August
to September obtained from the online O2O business
system to train the CVR model. We have two test sets:
  =   (),   ∈ R× , (17) one is one day dataset in September and another is three
days in October. Since user behavior evolves with time,
  =   (),   ∈ R× . (18) the closer the time is to the training data, the closer
the distribution of user behavior is to the training data,
, ∈ R× , 3.4. Cost Combination Module</p>
          <p>(14)
where ,  ∈ (, , ),  ,   ∈ R×  In this section, we embody CTR and CVR prediction tasks
is trainable parameters,   represents the correlation into a multi-task framework. The input of this module is
between the click sequence in dimension  and the the concatenation of the outputs from base module and
order sequence in dimension , , means that entire cost module.  and  are calculated by MLP
using the click additional information aggregation to network, respectively.
obtain the global conversion preference to update the
order sequence. The residual design is also used in this  =  (  ([, ℎ, ℎ, , ])), (22)
part.</p>
          <p>Finally, the aggregation of order sequence and click  =  (  ([, ℎ, ℎ, , ])). (23)
sequence can be obtained :
ℎ ∈ R3,
(15)
(16)
 
ℎ =  (‖ (, ) + ‖ (, )),</p>
          <p>ℎ =  (), ℎ ∈ R3,
where ‖ means concatenate of vectors.</p>
          <p>Ofline Cost Feature Module. In O2O scenario,
oflfine transportation costs also play an important role
in the conversion rate as users need to go to ofline
stores. We first construct the user’s historical
behavior sequences to represent the user’s historical click and
order transportation costs, and takes them as the input
of the  -layers Transformer encoder:</p>
        </sec>
      </sec>
      <sec id="sec-3-2">
        <title>To this end, we calculate the post-view click</title>
        <p>through&amp;conversion rate (CTCVR) by  =  *
 . The loss function used here is lambda loss [37].</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Experiments</title>
      <sec id="sec-4-1">
        <title>In this section, we evaluate the model performance of the proposed ECMM. We describe the experimental settings and experimental results as follows.</title>
        <sec id="sec-4-1-1">
          <title>4.1. Experimental Settings</title>
          <p>
            and the longer the relative time is, the user behavior task model for learning CTR and CVR in the industry. b)
distribution will change. Therefore the test sets in this ESMM+DIN [
            <xref ref-type="bibr" rid="ref38">20</xref>
            ]. Based on ESMM, users’ click sequence
experiment can efectively evaluate the accuracy and feature and the current store feature are introduced by
generalization of the model. The number of our training DIN method.
samples is approximately 1.1 billion, while the testing (2) Ablation: a) ECMM wo ofline and convAttn .
sets are 40 million and 100 million, respectively. Based on ECMM, we only use online convert cost
with
          </p>
          <p>Metric. The goal of our ranking task is to provide a out convert attention. b) ECMM wo ofline . Based on
list that is more likely to facilitate users’ conversion. The ECMM, we only use online convert cost. c) ECMM wo
evaluation metric used in this paper is NDCG. We have online and slidWinAttn. Based on ECMM, we only use
two ranking strategies: sorting by CTR and sorting by ofline convert cost without sliding window attention. d)
CTCVR. So we have NDCG sorted by CTR to predict real ECMM wo online. Based on ECMM, we only use ofline
click rate and NDCG sorted by CTCVR to predict real convert cost.
purchase rate. The calculation criteria are as follows: (3) ECMM variants: a) ECMM+dualInfo: Based on
ECMM, we calculate convert attention not only convert
  =  = Σ =1(2 − 1)/(1 + ) , click sequence information to the order sequence but
 Σ |=1|(2 − 1)/(1 + ) also convert order sequence information to the click
se(24) quence. b) ECMM+sepInput: Based on ECMM, we use
where  represents the length of the list of stores ranked the click feature as the input for the CTR network, the
by the model,  represents the label of the sample includ- order feature as the input for the CVR network.
ing click and order difering from the model task, and
|| represents the number of stores that label is not 4.2. Ofline Performance
zero.</p>
          <p>
            Compared Methods. Our baseline is a highly opti- The evaluation metric used in this paper is CTR-NDCG
mized ESMM model that incorporates a large number and CTCVR-NDCG. Table 1 shows the experimental
reof business features and handcrafted features. The to- sults of the comparison methods on two testing sets, from
tal number of features is 473. The embedding matrix of which we have:
dimension  is 10. We use the sequences feature from For the entire cost module, compared with ESMM,
users’ history for 180 days and the length  is 50. The ECMM can obtain a 0.35% gain on CTR-NDCG and 0.38%
numbers of Transformer layers  is 2. Because 80% of gain on CTCVR-NDCG 1. And all other ablation methods
users click sequence length is less than 10 and order se- and variants can also improve the model performance
quence length is less than 5, and considering the service after modeling users’ behavior sequences.
performance, the  of the sparse attention we chose is For online cost feature, compared with ESMM,
10. The dimension of the MLP used in the base module is ESMM+DIN adding click sequence has a certain increase
1024, and the dimension of the four-layer MLP used by in CTR- and CTCVR-NDCG. As showen in Figure 3,
the CTR and CVR networks is 512, 256, 128, 1 with ELU ECMM wo ofline and convAttn , which is further added
activation function, respectively. And all baselines take to the order sequence, slightly decreases in the
CTRinto account the statistical user features of online and
oflfine costs for fair comparison. We conduct comparative
experiments with three categories of methods:
(1) Baselines: a) ESMM [
            <xref ref-type="bibr" rid="ref1 ref17">10</xref>
            ]. An outstanding
multi
          </p>
        </sec>
      </sec>
      <sec id="sec-4-2">
        <title>1For large-scale datasets in industrial recommender systems, the</title>
        <p>improvement is considerable because of its hardness, and the testing
results in Section 3.3 further verify the significant improvement of
our proposal.</p>
      </sec>
      <sec id="sec-4-3">
        <title>NDCG, but greatly improves the CTCVR-NDCG. ECMM</title>
        <p>wo ofline indicates that the convert attention mechanism
can learn users’ order characteristics from click to order.</p>
        <p>These three methods show that it is efective to utilize
historical features to improve CVR prediction. The convert
attention brings 0.18% and 0.19% gains in CTR-NDCG
and CTCVR-NDCG.</p>
        <p>For ofline cost feature , the ECMM wo online and
slidWinAttn model that uses distance sequence features
brings stronger efects improve both CTR- and
CTCVRNDCG. As showen in Figure 4, comparing ECMM wo
online and slidWinAttn with ESMM, it can be seen that
the ofline transportation cost is indispensable for the
conversion rate prediction of O2O platform. And ECMM
wo online model introduced by our proposed slide
window attention brings greater gains by dynamic matching
user preference during diferent times. The sliding
window method brings 0.02% and 0.05% gains in CTR-NDCG
and CTCVR-NDCG.</p>
        <p>In order to explore whether the user’s historical 5. Conclusion
order will afect click, we further study with the
ECMM+dualInfo model that the order sequence trans- In this paper, inspired by the user sequential behaviors
mits information to the click sequence. It can be seen in O2O platform, a novel model is proposed to predict
that the click NDCG decreased by 0.05%, and the CTCVR- conversion rate. Further, introduce covert attention and
NDCG decreased by 0.06%. We separate the click and the sliding window attention in the cost module to learn users’
order features into the CTR network and CVR network to online behavioral regularity and ofline transportation
obtain the ECMM+sepInput model to verify the feature regularity. At the same time, ofline experiments have
impact of diferent task, and found that separate features proved the efectiveness of our proposed method to learn
will reduce model performance. users’ conversion from users’ click sequence to order</p>
        <p>To verify the generalization of our model instead of sequence, and the accuracy of the ranking list is
imiftting users over a certain period, we further evaluate proved by evaluating NDCG. Online experiments show
our method on a test set in October. The results are that ECMM method has a significant efect on
improvconsistent with the assessment in September. The ECMM
model shows that the advantage of considering users’
online behavioral and ofline transportation regularities
is helpful in predicting users’ current CTR and CTCVR.</p>
        <sec id="sec-4-3-1">
          <title>4.3. Online Evaluations</title>
        </sec>
      </sec>
      <sec id="sec-4-4">
        <title>Online A/B test was conducted in the recommender sys</title>
        <p>tem in 7 days in January 2022. For the control group,
10% of users were randomly assigned and presented in
a recommender system presented by a highly optimized
ESMM algorithm. For the experimental group, 10% of
users were randomly selected to use the ECMM method.
In the online experiment, we choose CTR and CTCVR as
evaluation indicators, where CTCVR represents the
purchase rate of each request. The result is shown in Figure
5. We can see that our proposed ECMM method
improves the CTR by 0.52% (p-value=0.00&lt;0.05) compared
with the baseline model, and the CTCVR by 0.73%
(pvalue=0.02&lt;0.05), which has a 1.8% (p-value=0.02&lt;0.05)
increase in total revenue. Here, total revenue increases
to 1.8% with a 0.45% increase in CTCVR means the model
provides users with higher price list. So far, the ECMM
method has been applied to the main online trafic and
has served more than hundreds of millions of users,
bringing a significant increase in the total revenue of Meituan.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>Acknowledgments</title>
      <sec id="sec-5-1">
        <title>This research was supported by the National Natural Science Foundation of China (NSFC) under Grant 72071029, 71974031 and 72231010. This research was also supported by Meituan.</title>
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ECMM method has been applied to the main online
trafifc, bringing a significant increase in the total revenue of
the enterprise.
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