Lecture video · L09 Interactivity

[Slide 1] Since week one you have known the punchline: a published report is interrogated, not read. Tonight, interrogation becomes a designed experience instead of a happy accident. The stakes run both directions — underbuilt, a report answers only the question its author guessed; overbuilt, it becomes a cockpit no executive will touch, where a forgotten filter ships a wrong number to a board deck. Interactivity is power steering: the reader drives, and you decide what the car can do. By the end of tonight you will have three filtering surfaces sorted, drill down and drillthrough separated for good, and the design frame your capstone will be graded on.

[Slide 2] Three different surfaces filter a page, and students conflate them for years unless somebody insists. Slicers are the reader's controls, and their great virtue is that their state is always visible. The Filters pane is the author's scoping tool — this page shows twenty twenty-six only — and it hides collapsed, which is fine for authorial decisions and terrible for anything a reader needs to know. And cross-filtering makes every visual a secret filter control: click a bar, everything moves, and after the click there is no visible trace of what happened. The design principle that falls out: behave as if every filter will one day be forgotten — because the forgetting is not a risk, it is a schedule.

[Slide 3] Prediction beat, and it is this lesson's whole argument in one story. A director escalates: the dashboard shows twenty-four point eight million, not sixty-six point eight — the data must be broken. No slicer shows any selection. One minute: what happened? The tell is the number itself. Twenty-four point eight million is exactly Furniture's total — someone clicked the Furniture bar, the click cross-filtered the card, and the state is invisible after the fact. Nothing is broken; the page just withheld its state. The immediate fix is one click on empty canvas. The design fix is two habits: reader-facing filters live in visible slicers, and every exploration page carries a clear-filters reset button — because the director's escalation was not a user error, it was a design gap wearing one.

[Slide 4] Two mechanics with names people swap for years. First, interactions: how one visual reacts to a click on another is a per-pair choice — filter, highlight, or none — and the default is not always right. A highlighted card shows an unchanged number over a changed context; readers misread it every time, so cards get Filter or a reasoned None. Second, the two drills. Drill down changes levels inside one visual: drill into Furniture and the bar re-renders as its four subcategories — Storage at six point eight one million, Bedroom, Seating, and Tables all within a million of it. Notice the evenness is itself the finding: no single line carries Furniture, which a merchandiser genuinely cares to know. Drillthrough is the other verb entirely: right-click a category, drill through, and land on a dedicated page already filtered to it — trend, subcategories, returns, top products. One detail page becomes a doorway behind every category in the report. Its honesty requirement: a dynamic title, built with SELECTEDVALUE, that says out loud which thing the page is currently about.

[Slide 5] Bookmarks capture a page's state and buttons apply it, and three uses cover nearly every honest need. The reset button — the antidote to the invisible filter. The view switch — revenue view, units view — where the bookmark must capture display only, because capturing data state makes the button stomp the reader's slicers; you will build that bug on purpose this week and fix it. And a few guided states, sparingly — a page that needs ten bookmarks is a slideshow asking for its native medium. All of it serves the lesson's design frame: every page is an answer page or an exploration page. The answer page states findings — titles doing the talking, one slicer at most, fifteen seconds enough. The exploration page hands over the keys. The classic sin is one page trying to serve both audiences — executives lost in controls, analysts starved of them. Split it, and let each page be honestly itself. Your capstone is graded on exactly this separation.

[Slide 6] Tonight in five lines. Three filtering surfaces, kept deliberately apart — and designed for the day their state is forgotten. The twenty-four point eight million escalation taught the invisible-filter problem; the reset button and visible-state discipline answer it. Drill down descends inside a visual — Furniture's four even engines — while drillthrough departs to a page about one thing, wearing a title that confesses its filter. Bookmarks earn three uses and resist sprawl. And with that, Module Three is complete: you can choose the honest chart, extend it into maps and scatters and heat grids without lying, and wrap the whole thing in interactivity a reader can drive without crashing. This week's Hot practice makes you hand the cockpit to a successor — documentation included. Next module, the last one: report design as a discipline, the Power BI Service where all of this ships, and the AI features — used with exactly the skepticism you have been practicing for eleven weeks.