Case Study Case write-up submission guidelines Part A You are expected to submit a case summary of not more than 500 words. Below three points will provi

Case write-up submission guidelines

Part A

You are expected to submit a case summary of not more than 500 words. Below three points will provide you with an understanding of how to prepare the case summary for submission.

  1. Start with the problem or need of the project you are solving. At the beginning of your executive summary, start by explaining why this document (and the project it represents) matter.
  2. Outline the recommended solution or the project’s objectives.
  3. Explain the solution’s value

Part B

You are expected to answer the following Case Questions (Word limit per question is 200 words)

Q1. Which assumptions underlie your analysis?

Q 2. What would you advise regarding the performance of the new Data Science algorithm based on the statistical analysis of the Hypothesis? Which algorithm is performing better?

Please Note: Use Times New Roman. Label parts and question numbers clearly.

Rev. Mar. 7, 2017

A/B Testing at Vungle

Andrew Kritzer and Hammond Guerin stared at the screen and then at each other. It was June 30, 2014—
six weeks since they had graduated from the Darden School of Business. The ad-serving algorithm Kritzer and
Guerin had spent six months developing for Vungle, a mobile advertising company, seemed to be
outperforming the company’s current algorithm. But they did not want to start celebrating too soon. Could
their algorithm really deliver the type of improvement they had promised Vungle’s CEO? Would install rates
of advertised apps really increase? Would Vungle see an increase in ad-serving efficiency as a result?

Neither Kritzer nor Guerin could afford for the algorithm to disappoint. Now that he had graduated,
Kritzer was headed to LinkedIn, having left a legend among MBA students for his appreciation of data science,
tech, and media and raising expectations for what Darden students knew and could learn about data science,
analytics, and the ever-growing world of big data. His work on the Vungle project during his second year had
received a lot of attention, and he was looking forward to having the results support the effort.

Guerin’s data science capabilities were also legendary among his MBA peers. He won every school
forecasting competition, and his data mining algorithms even beat those of the professional consultants who
did classroom visits. Late in his second year, Guerin decided to turn down a generous offer from a well-known
consulting firm in favor of an offer from Vungle for an annual salary of $100,000 and stock options to serve as
the head of Vungle’s brand new data science team out in the company’s San Francisco headquarters. The job
was a dream for the computer scientist turned MBA. He and his wife were already house hunting in the Bay
Area, looking for the right place to raise their baby daughter.

Company Overview

Vungle was an in-app video advertising company. With 70 employees and $25.5 million from three rounds
of investments, Vungle was routinely listed as one of the most promising start-ups operating in Silicon Valley.1
The three-year-old company offered a platform that embedded video ads in mobile apps to encourage users to
download and install additional apps. It was estimated that more than 100 million people saw an advertisement
enabled by Vungle each month.2

1 Anthony Ha, “In-App Video Ad Startup Vungle Raises $17M More,” TechCrunch, February 6, 2014,
series-b (accessed Aug. 23, 2014).

2 Steven Loeb, “In-App Video Advertising Platform Vungle Raises $17M,” VatorNews, February 6, 2014,
video-advertising-platform-vungle-raises-17m (accessed Aug. 23, 2014).

This field-based case was prepared by Yael Grushka-Cockayne, Assistant Professor of Business Administration, and Kenneth C. Lichtendahl Jr.,
Associate Professor of Business Administration, both from the Darden School of Business; and by Bert De Reyck, Professor and Head of the Department
of Management Science and Innovation, and Ioannis Fragkos, Research Associate, both of University College London. It was written as a basis for class
discussion rather than to illustrate effective or ineffective handling of an administrative situation. Copyright ã 2015 by the University of Virginia Darden
School Foundation, Charlottesville, VA. All rights reserved. To order copies, send an e-mail to No part of this publication
may be reproduced, stored in a retrieval system, used in a spreadsheet, or transmitted in any form or by any means—electronic, mechanical, photocopying, recording, or otherwise—
without the permission of the Darden School Foundation.

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Page 2 UV6965

Vungle was founded in 2011 by two young entrepreneurs from the United Kingdom, Zain Jaffer and Jack
Smith, during their graduate studies at University College London. Initially a video ad production firm, Vungle’s
expenses in its first year were running too high and revenue was not reaching the founders’ expectations. Late
in 2011, Jaffer borrowed funds from his then girlfriend (and future wife) and his business professor, Bert De
Reyck. Each invested $15,000 and the company remained afloat.3

The turning point for Vungle came in 2012, when the two founders creatively used their own video
production technology to get the attention of the San Francisco–based start-up incubator AngelPad. In doing
so, they beat 2,000 applicants for the final slot in the incubator program. This opportunity provided Vungle
$120,000 in seed funding. Jaffer moved to San Francisco to serve as the firm’s CEO and remained in that
position. He was profiled in a “35 Under 35” list by Inc. magazine in 2014.4

The Mobile Advertising Ecosystem: Market, Operations, and Pricing

In 2013, the average U.S. consumer spent two hours and 42 minutes on mobile devices per day; 86% of
that was spent in apps, the clear dominant form of mobile usage.5 The growth in the mobile market and the
extensive time spent in apps introduced a new advertising channel. According to the Mobile Marketing
Association, 75% of ads served to mobile consumers in 2013 were served while they were using apps.6 Mobile
in-app ads experienced a 60% annual growth in 2013 and were expected to surpass PC online ad revenues by

By 2014, in-app video advertising was replacing mobile banner ads—the latter offered a lower-quality user
experience and were typically clicked on accidentally. The in-app video ads were typically 15 seconds long and
promoted a new app or product. Apple’s iOS system accounted for 80% of ads being served. Video ads peaked
during prime-time TV hours.8

Four parties participated in the in-app mobile advertisement channel. The user of the mobile device (user),
the owner of the app being used (publisher), the sponsor of the video ad the user was exposed to (advertiser), and
the platform that matched the choice of ad to a specific user (e.g., Vungle). In the mobile advertising domain,
supply was considered to be the slots available for showing ads, and demand consisted of the advertisers willing
to buy the supply by placing ads.

When the user launched an app, his or her device would send a request to Vungle for an ad. For instance,
suppose user Chris was playing Sonic Dash by the publisher Sega. Vungle’s platform would then determine the
best ad to serve to Chris while he played Sonic Dash. Assume Vungle decided to serve Chris an ad for the game
Hay Day (the advertiser; see Exhibit 1 for a schematic of this process). Assuming Chris was still playing Sonic
Dash when the ad was served, then Chris would see the video for Hay Day. If Chris was interested in learning
more about Hay Day, he would click on the ad and be redirected to the app store. Chris might then decide to
install Hay Day.

3 Laura Montini, “Creating Ads That Blend In to Stand Out,” Inc., June 24, 2014,
blend-in-to-stand-out.html (accessed Jan. 15, 2015).

4 Donna Fenn, “Generation Why Not: Meet the 35 Under 35, Class of 2014,” Inc., July/August 2014,
35-2014.html?cid=readmore (accessed Jan. 15, 2015).

5 Ewan Spence, “The Mobile Browser Is Dead, Long Live the App,” Forbes, April 2, 2014, (accessed Aug. 23, 2014).

6 Spence.
7 Dean Takahashi, “Mobile In-App Ad Revenues Will Surpass PC Online Display Advertising by 2017,” VentureBeat, March 26, 2014, (accessed Aug. 23, 2014).
8 Christopher Heine, “75% of Mobile Video Ads Happen In-App,” AdWeek, April 24, 2014,

video-ads-happen-app-157217 (accessed Jan. 15, 2015).

This document is authorized for use only by Ritesh Karnam in Data and Decisions – DAT-3510 – FMIB1 at Hult International Business School, 2022.

Page 3 UV6965

In most cases, payment was made by the advertiser upon installation. Publishers typically received 60% of
the revenues and the ad provider the remaining 40%. See Figure 1 for the conversion funnel depicting how an
install is achieved. Of all ad requests, most were served and became impressions. When at least 80% of a video ad
was watched, it was considered complete. When the user clicked on the ad to get more information, it was counted
as a click. The process could then result in an install.

Figure 1. Mobile in-app advertising funnel.







Fill Rate

letion Rate


lick-through Rate


ion Rate


Source: Created by case writer.

Ads were monetized at all different points along the funnel—whether CPI (cost per install), CPC (cost per
click), CPCV (cost per completed view), or CPM (cost per 1,000 views). The vast majority of ads were CPI.

On a typical day, using its current ad-serving algorithm, Vungle experienced a 98% fill rate, 88% completion
rate, 5% click-through rate, and 0.5% conversion rate. The funnel for Vungle narrowed substantially at the end.
Small improvements in the click-through or conversion rates could have a large effect on Vungle’s revenue.
The effectiveness of an app-promotion campaign and the success of the serving platform were typically
measured by eRPM, or effective revenue (for both publisher and Vungle) per 1,000 impressions,9 which could
vary from $2 to as high as $7 per campaign.

A/B Testing and the Data Science Project

Kritzer and Guerin were tasked with developing an ad-serving learning algorithm. Their data science
approach would use historical information about users, publishers, and install rates to determine which ad
campaign to serve in order to increase the chance of a conversion and, more specifically, eRPM. If the system
proved successful, implementing it would require regular updates to the model by a data scientist, most likely
Guerin himself.

Jaffer consulted with Vungle’s chief technology officer, Wayne Chan, on how best to test the developed
algorithm. Chan planned to test the developed method in parallel with the existing Vungle algorithm. As was
typical in such experiments, the two conditions, A (Vungle’s existing algorithm) and B (the data science
approach) would be evaluated in parallel on randomly assigned users. Since Kritzer and Guerin’s algorithm was
new and unproven, Chan’s team thought it would make sense to direct only 1/16th of the users to the B

9 See

This document is authorized for use only by Ritesh Karnam in Data and Decisions – DAT-3510 – FMIB1 at Hult International Business School, 2022.

Page 4 UV6965

condition. The other randomly assigned 15/16ths of users would receive an ad based on the existing algorithm
(i.e., the A condition).

Users were assigned to the A or B algorithm using a process called MD5 hashing. An MD5 hash transforms
each user ID into a unique 32-character hexadecimal string. Each character of the hexadecimal string could be
0–9, A, B, C, D, E, or F—16 options in total. Each character occurred with equal likelihood, making it simple
for Vungle to direct traffic in 1/16th increments using a logic statement (assuming that the original string
was random).

The parallel run of the two algorithms began on June 1, 2014. Jaffer was excited to see if B would
outperform A and, if so, what the financial benefits would be. He also wondered how long Chan would have
to wait to declare a winner. Would a few days be enough time? Or would he need to wait longer? After two
weeks, B was looking pretty good. Its daily eRPM was on average $0.131 higher than A’s. Would this translate
into annual revenues worthy of the necessary data science investment? Exhibits 2 and 3 provide the daily
results of the A/B test.10

Thinking about his new role at Vungle, Guerin was curious to see how the superior condition would be
chosen. How would one conclude that B was better than A? If he could be confident about such a conclusion,
he would be able to develop a robust testing platform for many future experiments.

10 All numbers in the exhibits are disguised and serve illustrative purposes only.

This document is authorized for use only by Ritesh Karnam in Data and Decisions – DAT-3510 – FMIB1 at Hult International Business School, 2022.

Page 5 UVA-QA-0821

Exhibit 1

A/B Testing at Vungle

Schematic of the Vungle Platform Role

Source: Company document; used with permission.

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Page 6 UV6965

Exhibit 2

A/B Testing at Vungle

Data from Vungle A Test Condition

Date Impressions Completes Clicks Installs eRPM
1-Jun-14 6,777,407 5,978,434 345,309 31,119 3.327
2-Jun-14 6,004,310 5,331,727 299,732 24,601 2.943
3-Jun-14 5,832,627 5,193,549 291,384 24,220 3.025
4-Jun-14 5,875,702 5,227,917 295,099 23,382 2.985
5-Jun-14 6,843,405 6,111,378 339,529 27,725 3.076
6-Jun-14 7,790,350 6,981,471 392,987 31,820 3.137
7-Jun-14 8,643,430 7,733,750 444,682 38,119 3.322
8-Jun-14 8,929,848 7,993,169 449,680 38,260 3.269
9-Jun-14 8,075,571 7,259,148 392,829 32,825 3.153
10-Jun-14 7,726,694 6,941,293 382,769 31,609 3.237
11-Jun-14 7,781,497 6,999,630 389,369 31,683 3.199
12-Jun-14 7,770,595 6,984,082 391,254 30,985 3.206
13-Jun-14 7,916,282 7,091,841 407,582 31,679 3.246
14-Jun-14 8,724,061 7,782,877 459,952 36,773 3.482
15-Jun-14 9,027,910 8,075,018 465,869 37,701 3.467
16-Jun-14 7,957,999 7,149,399 395,612 31,098 3.245
17-Jun-14 8,102,155 7,283,722 404,716 31,359 3.315
18-Jun-14 8,043,855 7,229,427 407,014 32,414 3.460
19-Jun-14 8,073,992 7,226,473 403,193 31,665 3.583
20-Jun-14 8,085,480 7,224,975 406,766 30,473 3.479
21-Jun-14 8,760,745 7,825,166 454,646 33,178 3.475
22-Jun-14 8,884,803 7,937,481 453,647 33,543 3.459
23-Jun-14 8,040,402 7,182,500 401,226 28,864 3.337
24-Jun-14 7,882,136 7,013,876 389,975 30,302 3.326
25-Jun-14 7,782,617 6,932,529 385,477 30,369 3.367
26-Jun-14 7,734,447 6,887,125 388,935 30,920 3.530
27-Jun-14 7,891,063 7,025,318 409,449 31,689 3.672
28-Jun-14 8,460,726 7,487,623 457,487 34,664 3.830
29-Jun-14 8,849,803 7,785,905 478,901 36,467 3.777
30-Jun-14 8,189,490 7,233,880 411,884 32,160 3.484

Source: Created by case writer.

This document is authorized for use only by Ritesh Karnam in Data and Decisions – DAT-3510 – FMIB1 at Hult International Business School, 2022.

Page 7 UV6965

Exhibit 3

A/B Testing at Vungle

Data from Vungle B Test Condition

Date Impressions Completes Clicks Installs eRPM
1-Jun-14 569,044 499,235 28,035 2,111 2.953
2-Jun-14 505,963 447,695 24,621 1,713 2.587
3-Jun-14 492,804 437,495 24,070 1,705 2.755
4-Jun-14 498,772 442,791 25,023 1,801 3.004
5-Jun-14 491,463 436,858 24,337 1,875 3.243
6-Jun-14 509,657 454,702 25,223 1,932 3.430
7-Jun-14 564,247 502,016 28,127 2,221 3.438
8-Jun-14 575,302 512,228 28,200 2,203 3.455
9-Jun-14 523,689 469,082 25,075 1,950 3.272
10-Jun-14 504,636 452,753 24,414 1,914 3.394
11-Jun-14 506,060 454,773 24,637 1,839 3.366
12-Jun-14 505,083 452,687 24,879 1,812 3.321
13-Jun-14 513,106 458,354 26,018 1,893 3.488
14-Jun-14 562,772 499,196 29,088 2,076 3.525
15-Jun-14 586,702 522,522 29,163 2,097 3.341
16-Jun-14 516,148 462,646 24,635 1,805 3.297
17-Jun-14 526,671 471,763 25,325 1,786 3.333
18-Jun-14 526,713 471,137 25,761 1,912 3.604
19-Jun-14 531,452 472,466 25,361 1,740 3.847
20-Jun-14 420,187 373,085 20,629 1,360 3.887
21-Jun-14 548,116 485,150 27,480 1,668 3.694
22-Jun-14 581,785 515,575 28,701 1,816 3.636
23-Jun-14 525,631 466,427 25,462 1,618 3.602
24-Jun-14 517,748 455,814 24,808 1,715 3.418
25-Jun-14 511,505 451,388 24,894 1,725 3.408
26-Jun-14 508,097 448,333 25,111 1,773 3.722
27-Jun-14 518,004 457,335 25,832 1,852 3.939
28-Jun-14 562,854 494,686 28,491 2,041 4.073
29-Jun-14 583,732 510,194 29,483 2,168 4.051
30-Jun-14 537,433 470,054 26,669 1,910 3.687

Source: Created by case writer.

This document is authorized for use only by Ritesh Karnam in Data and Decisions – DAT-3510 – FMIB1 at Hult International Business School, 2022.

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