# Read scatterplots with Book Isle: keep each observation’s x and y together

Language: en
Canonical: [Read scatterplots with Book Isle: keep each observation’s x and y together](<https://allluckly.cn/en/guides/nasbook-scatterplot-observation-pair-notes/>)
中文：[中文 HTML](<https://allluckly.cn/guides/nasbook-scatterplot-observation-pair-notes/>)
English: [English HTML](<https://allluckly.cn/en/guides/nasbook-scatterplot-observation-pair-notes/>)
Published: 2026-11-08T00:00:00+08:00
Modified: 2026-11-08T09:34:15+08:00
Author: Bison

Use five invented coordinate pairs to check variables, units, positions and overlaps without separating pairs or inferring causation from association.

English translation of the [Chinese original](<https://allluckly.cn/guides/nasbook-scatterplot-observation-pair-notes/>), translated on 2026-11-08. Original publication dates, attribution, code and version notes are retained.

A scatterplot point usually contains two values from the same observation. Do not read the horizontal axis as one list and the vertical axis as another and pair them arbitrarily. Read a lawfully obtained illustrated document in Book Isle and record variables, units and point evidence in your own notes. The practice coordinates are invented, not a study of learning effectiveness. The app displays documents and stores reading records; readers check and interpret points manually without automatic scatter recognition or correlation calculation.

## Record the plot’s exact reading location

Open a file containing a scatterplot in Book Isle. Record title, edition, chapter, figure number and caption, and add an available bookmark for return. In PDF distinguish printed page from file page; for reflowable text prefer chapter and caption phrases to a page number that changes with font size. Use viewing or zoom controls actually available for that format. Obtain a clearer lawful original if labels remain unreadable instead of guessing. A search hit mentioning a figure number is not necessarily the figure; verify caption and neighbouring text. Manually record locations when selection is unavailable, without assuming every image can be excerpted.

## Write both variables and units in full

Copy horizontal variable, unit and scale range, then the same three vertical details, noting logarithmic scales or truncated axes. The invented example uses minutes of reading prior to one exercise horizontally and correct answers out of six vertically, both on ordinary linear scales. Minutes and answer counts are not interchangeable, and an upper limit of six does not mean six percent. Write thousand/million multipliers explicitly when present; mark unreadable units as unresolved rather than guessing from height. Keep real-source variables separate from this example and never transfer its units to another plot. Complete axis information comes first.

## Keep five practice records as intact pairs

Write A as one minute/two answers, B two/four, C two/one, D three/three and E four/five, giving (1,2), (2,4), (2,1), (3,3), (4,5). Keep each letter with its pair rather than sorting the five horizontal and vertical values independently and recombining them. If the file lacks this practice plot, draw it on paper; Book Isle need not generate it. Locate each intersection by moving up from x and across from y, then reread its letter to verify pairing. These five invented observations train reading only and describe no real reader performance.

## Distinguish equal x values from identical observations

B and C both have x=two minutes but y=four and one answers. They belong at different heights in one vertical column, not a single averaged point at 2.5 answers. Equal x can have different y; do not delete observations for failing a function exercise. Identical x and y from two records may overlap, so one visible mark does not establish one sample. Check legend, transparency explanation or data table. Record unknown multiplicity when unspecified rather than inventing people. None of these five pairs overlaps completely; distinguish shared x from complete overlap.

## Describe the cloud with limited trend language

Once plotted, describe an overall tendency toward higher y at higher x while noting that B and C differ at equal reading time. Do not connect successive points as a time path: A–E label observations, not five consecutive days. Distinguish fitted model lines from observed points; a line passing somewhere does not establish a sample there. Do not invent a correlation coefficient or conclude that one extra minute guarantees one extra correct answer. Preserve visible curvature or groups instead of ignoring structure and exceptions to force a positive-correlation statement.

## Separate association from causal explanation

Use your own textual labels to separate what the plot shows from explanations needing verification. Visible evidence includes positions and co-variation; possible explanations include task difficulty, prior familiarity or other factors. These are note labels, not automatic statistical columns. An observational plot alone cannot establish that reading time caused answer changes; invented practice data has no real research design at all. If the author claims causation, inspect methods for assignment, intervention and controls. Record missing support instead of supplying your own guesses as the author’s evidence. Rejecting an excessive claim does not prove no relationship exists.

## Return to the original for unusual points and reading error

For a point far from the cloud, first verify coordinates, units, legend colour and image clarity rather than deleting it. Check decimal marks, minus signs and thousandfold multipliers. A logarithmic axis needs ratio-based reading, not this example’s linear spacing. Record an approximate interval for a blurred mark rather than false decimal precision. Separate unresolved from confirmed items and revisit the same caption through its bookmark. Exit and reopen reading once to verify the record reaches the plot rather than a neighbouring page. Identify return failures by edition, figure number or page sequence; a note alone does not guarantee correct location.

## Test the notes by explaining one point

Set the trend description aside and explain C from notes alone: one invented observation, two minutes of reading and one correct answer out of six. It shares B’s x but not y, is not a revised B and is not an average. State that all five points are practice data and why causation does not follow. Return to variables or observation identity if this explanation is incomplete rather than ending with vague advice to inspect more data. Save location, axes, pairs, visible description and unresolved explanations together. Start a new record for another figure so units, sample counts and conclusions do not merge.

## Related tutorials and sources

[Read logarithmic plots in Book Isle: interpret equal distances as ratios, not differences](<https://allluckly.cn/en/guides/nasbook-log-axis-ratio-reading/>); [Read arguments in Book Isle: separate claims, evidence and inferential links](<https://allluckly.cn/en/guides/nasbook-claim-evidence-bridge/>).

Sources checked on 8 November 2026: the [official Book Isle App Store listing](<https://apps.apple.com/cn/app/id6766198898>) and [Apple Lookup](<https://itunes.apple.com/lookup?id=6766198898&country=cn>) show version 1.1.4, requiring iOS / iPadOS 15.6 or later. This workflow uses local reading, search, bookmarks and notes for manual checking. Readers record the samples and conclusions; automatic chart recognition, statistical testing or proof verification is not assumed. Confirm available controls against the installed version and file type. The exercise does not claim step-by-step device testing in this batch.

Method reference: [NIST’s scatterplot account](<https://www.itl.nist.gov/div898/handbook/eda/section3/scatterp.htm>) supports paired-variable reading and the distinction between association and causation. The five A–E pairs are original practice data, not findings from that institution.