1. Lighthouse

Level 2 · Check and build the web funnel in Excel

The request

From Jordan Reyes, Head of Marketing

“Priya sent me 2025 by month and device: sessions, sessions with three or more pages, and conversions. Can you check it holds together, then turn it into one small funnel table by device? I want to see where mobile loses people.”

Your goal

Step 1 of 2. Check the export. In G2:G37, return "ok" if converted (E) is less than or equal to engaged (D), otherwise "check" (one formula, filled down). In J2, count the rows marked "check" with COUNTIF. In J3, total the sessions in C2:C37.

  • Fill G2:G37, J2:J3 with the right valuesnot done yet
  • With formulas, not typed numbersnot done yet
  • Use IF COUNTIF SUMnot done yet

Step 1 · your sheet

Excel
The sheet for this level
ABCDEFGHIJKLMNOP
1monthdevicesessionsengagedconvertedcheck
22025-01desktop35113411Rows to check
32025-01mobile5062297Total sessions
42025-01tablet103472
52025-02desktop27012512devicesessionsengagedconvertedengaged %conversion %engaged to converted
62025-02mobile42420211desktop
72025-02tablet85433mobile
82025-03desktop39317317tablet
92025-03mobile58226515
102025-03tablet103493
112025-04desktop35615516
122025-04mobile60327219
132025-04tablet99433
142025-05desktop4001738
152025-05mobile70532010
162025-05tablet97422
172025-06desktop34516116
182025-06mobile62126810
192025-06tablet108474
202025-07desktop36816418
212025-07mobile62627919
222025-07tablet119564
232025-08desktop3541609
242025-08mobile68329010
252025-08tablet104483
262025-09desktop40818118
272025-09mobile72534714
282025-09tablet106531
292025-10desktop41418617
302025-10mobile81637615
312025-10tablet143600
322025-11desktop79334947
332025-11mobile157370457
342025-11tablet24310712
352025-12desktop80035028
362025-12mobile154364350
372025-12tablet2561129
38
39

Loading the editor…

    ResultPress Check to compare G2:G37, J2:J3

    Mote checks your result

    Press Check. Each right cell becomes a firefly in your lantern.

    Step 2 · your sheet

    Excel
    The sheet for this level
    ABCDEFGHIJKLMNOP
    1monthdevicesessionsengagedconvertedcheck
    22025-01desktop35113411okRows to check0
    32025-01mobile5062297okTotal sessions16225
    42025-01tablet103472ok
    52025-02desktop27012512okdevicesessionsengagedconvertedengaged %conversion %engaged to converted
    62025-02mobile42420211okdesktop
    72025-02tablet85433okmobile
    82025-03desktop39317317oktablet
    92025-03mobile58226515ok
    102025-03tablet103493ok
    112025-04desktop35615516ok
    122025-04mobile60327219ok
    132025-04tablet99433ok
    142025-05desktop4001738ok
    152025-05mobile70532010ok
    162025-05tablet97422ok
    172025-06desktop34516116ok
    182025-06mobile62126810ok
    192025-06tablet108474ok
    202025-07desktop36816418ok
    212025-07mobile62627919ok
    222025-07tablet119564ok
    232025-08desktop3541609ok
    242025-08mobile68329010ok
    252025-08tablet104483ok
    262025-09desktop40818118ok
    272025-09mobile72534714ok
    282025-09tablet106531ok
    292025-10desktop41418617ok
    302025-10mobile81637615ok
    312025-10tablet143600ok
    322025-11desktop79334947ok
    332025-11mobile157370457ok
    342025-11tablet24310712ok
    352025-12desktop80035028ok
    362025-12mobile154364350ok
    372025-12tablet2561129ok
    38
    39

    Loading the editor…

      ResultPress Check to compare J6:O8

      Mote checks your result

      Press Check. Each right cell becomes a firefly in your lantern.

      The lesson

      What the sheet holds

      Priya’s export has one row per month and device for 2025, 36 rows in all:

      column holds
      A, B month and device
      C sessions
      D engaged sessions: 3 or more pages viewed
      E converted sessions

      A funnel follows the same sessions through stages that narrow down: sessions, engaged, converted. The rates between stages show where people drop out.

      Step 1: check before you build

      An export is someone else’s query. A funnel has a built-in rule you can test on every row: a later stage can never be bigger than an earlier one. In this data a session only converts after at least three pages, so converted must be less than or equal to engaged:

      G2   =IF(E2<=D2,"ok","check")

      Fill it down to G37, then count the failures and total the traffic:

      J2   =COUNTIF(G2:G37,"check")
      J3   =SUM(C2:C37)

      J2 should be 0. J3 is worth comparing with a number the reader already knows, here the 2025 total on the web dashboard. When both agree, the export holds the right rows.

      Step 2: one SUMIFS for the whole table

      The table needs nine totals: three devices by three measures. Because the table’s columns J, K, L sit in the same order as the data’s columns C, D, E, one formula can do all of them if each reference is locked exactly as much as it must be:

      J6   =SUMIFS(C$2:C$37,$B$2:$B$37,$I6)
      reference lock why
      C$2:C$37 rows only filled right, it becomes D and E
      $B$2:$B$37 column and row the device column never moves
      $I6 column only every cell reads its own row’s device

      Then the rates, each a stage divided by the one before it or by all sessions:

      M6   =K6/J6      engaged %
      N6   =L6/J6      conversion %
      O6   =L6/K6      engaged to converted

      Reading the result

      Mobile and desktop browse alike: 44.6% and 44.0% of sessions reach three pages. The gap opens at the last step, where 9.4% of engaged desktop sessions convert against 5.6% on mobile. That points the mobile team at the basket, sign-in and payment, not at the product pages.

      The full analysis in SQL or pandas goes one step further: it removes anonymous sessions, which never convert in this data, and follows the rates year by year as traffic moves to mobile. The sheet covers 2025 only, so it cannot show that shift.

      Pitfalls

      • Averaging monthly rates gives quiet months the same weight as busy ones. Total, then divide.
      • A fully locked sum range ($C$2:$C$37) repeats the first column across the table.
      • Typing the device into the formula ("mobile") breaks the fill down.

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