Learn Python Blog – Page 2 – Be on the Right Side of Change

60/40 Portfolio Max Drawdown: −35.8% in 2008, but Only 3.7 Points of Cushion in 2022 (Python)

November 1, 2026 by Michael

Featured bar chart of max drawdowns, 100% stocks vs 60/40, daily data 1986-2026: 1987 -33.1% vs -21.7%, 2000-02 -47.5% vs -25.9%, 2008-09 -55.3% vs -35.8%, 2020 -33.8% vs -21.6%, 2022 -24.6% vs -20.9%, a gap of only 3.7 points

60/40 portfolio max drawdown: −35.8% in 2008 vs −55.3% for stocks, but only a 3.7-point cushion in 2022. Daily data since 1986, tables, Python.

KDP Paperback Royalty Calculator: One Cent Pays 3.6× More, and Every 100 Pages Costs $1.20

October 31, 2026 by Michael

Featured line chart of KDP paperback royalty for a 300-page black-ink book on Amazon.com by list price: $0.39 at $9.98 in the 50% band jumps to $1.39 at $9.99 in the 60% band, 3.6 times more for one cent

KDP paperback royalty calculator: 60% at $9.99+, 50% below, minus $1 + $0.012/page. A 300-page book pays $0.39 at $9.98, $1.39 at $9.99.

Best AI for Editing a Novel: Hand AI the $1,740 Pass, Keep the $960 Human Proofread

October 31, 2026 by Michael

Featured bar chart of editing cost per 60,000-word romance: $4,020 all human, $2,310 with an AI structure pass, $1,000 with AI structure and line passes plus a human proofread, $40 all AI

Best AI for editing a novel, by the numbers: AI takes the $1,740 structural pass, a human proofreads, and a 60k romance edit drops from $4,020 to $1,000.

KDP Passive Income Isn’t Passive: $10K-a-Month Authors Spend $4,500 a Month on Marketing

October 31, 2026 by Michael

Featured bar chart of average monthly marketing spend by indie author income bracket from the Written Word Media 2025 survey: $81 under $100, $152, $275, $478, $1,362, and $4,500 a month for authors earning over $10,000 a month

KDP passive income is real but not hands-off: $10k/month authors spend $4,500/month on marketing, and a stalled catalog halves every 18 months. The math.

How Long Does It Take the Stock Market to Recover From a Crash? Median 2.1 Years (Python)

October 30, 2026 by Michael

Featured bar chart of the 12 S&P 500 declines of 20% or more since 1928, years from record high to the next record high: 1929 25.0 years, 1973 7.5, 2000 7.2, 2007 5.5, all others 0.5 to 3.3 years; median recovery 2.1 years

How long does it take the stock market to recover from a crash? S&P 500 median: 2.1 years across 12 crashes since 1928. Depth table, dividends, Python.

Kindle Countdown vs Free Book Promotion: A Free Reader Is Worth 83% Less, and Free Still Wins 4.6× on a Series

October 30, 2026 by Michael

Featured bar chart of royalties per promotion, $0.99 Kindle Countdown Deal vs Free Book Promotion: standalone $20 vs $0, 2-book series $61 vs $220, 3-book series $93 vs $389, 5-book series $152 vs $704; free out-earns the deal 4.6 times on a 5-book series

Kindle Countdown vs free book promotion: a free reader is worth 83% less, yet free earns 4.6× more on a 5-book series. KDP rules, math, 2.2% break-even.

KDP Audiobook Royalty: 40% With Virtual Voice, and the 1,722-Sale Math vs a Paid Narrator

October 30, 2026 by Michael

Featured line chart of net audiobook royalties by sales at $14.99: KDP Virtual Voice at 40% with $0 cost, ACX narrator at 50% minus $2,581 up front, and ACX royalty share at 25%; the paid narrator overtakes Virtual Voice only after 1,722 sales

KDP audiobook royalty: Virtual Voice pays 40% ($6 per $14.99 sale) for $0. A $2,581 ACX narrator needs 1,722 sales to win. Rates, math, Kindle+ catch.

KDP Box Set: One $12.99 Sale Now Out-Earns the Average Reader’s 5-Book Run

October 29, 2026 by Michael

Featured bar chart of royalty per buyer: one $3.99 single $2.69, a $12.99 box set before July 7, 2026 at 35% $4.55, a $9.99 box set $6.47, a $12.99 box set now at 70% $8.57 (+88%), and the average Book-1 buyer across five singles $8.28

KDP box set math: since July 2026 a $12.99 box keeps 70% ($8.57 a sale), beating a reader’s 5-book run. Pricing, KU 3,000-page cap, setup checklist.

Sharpe Ratio vs Sortino Ratio: A Sharpe Tie Became 2.08 vs 1.65 (Python)

October 29, 2026 by Michael

Featured scatter chart of annualized Sharpe ratio vs Sortino ratio for eight assets, Oct 2016 to Sep 2026: Bitcoin and QQQ have nearly the same Sharpe (0.98 and 0.97) but Sortino ratios of 2.08 and 1.65, a 0.43 gap

Sharpe ratio vs Sortino ratio in Python: Bitcoin and QQQ tied on Sharpe (0.98 vs 0.97) over 10 years, but Sortino scored them 2.08 vs 1.65. Here’s why.

How to Write a Romance Book Series When Book 1 Earns Only 32% of the Money

October 29, 2026 by Michael

Featured bar chart: in Kindlepreneur's five-book read-through example, 100 readers start Book 1, 65 read Book 2, 50 Book 3, 48 Book 4 and 45 Book 5, so Book 1 is only 32% of the series' 308 reads

How to write a romance book series: Book 1 earns only 32% of a 5-book series’ reads. Plan 5 books, fix the Book 1 to 2 leak, and keep the trope promise.

KDP Keywords Examples: 7 Filled Boxes for a Romantasy Series (Plus the $4.41 Reader Math)

October 28, 2026 by Michael

Featured bar chart: one new Book-1 reader bought through Amazon ads costs $3.80 at the $0.38 books average CPC, $7.00 at $0.70 and $9.00 at $0.90 fiction CPC with 10% conversion, while a keyword-found reader costs $0 per click and is worth $4.41 in Kindle Unlimited page reads across a 5-book series

KDP keywords examples: 7 filled boxes (50 characters each) for a romantasy series, KDP’s avoid list, a series keyword map, and why a reader is worth $4.41.

Best AI for KDP: The Draft Is Only 0.6% of Your Book Budget (Pick the AI That Saves Edits)

October 28, 2026 by Michael

Featured bar chart of what one 60,000-word romance costs to produce at Reedsy average rates: developmental edit $1,740, copy edit $1,320, proofread $960, cover design $720 and the AI draft $30, which is 0.6% of the $4,770 total

Best AI for KDP? The draft is only 0.6% of a $4,770 pro-edited romance. Pick the AI that saves editing passes, with a Python budget calculator.