Some people have more ways into a sample.

INSTRUMENTS / NETWORKS & PERCEPTION

Constructed example

Change the network. Change the view.

Change an input. Inspect every step. Keep a fixed record.

A working copy · changes stay here until you save

networks-v1

01 / THE QUESTION

Who is most likely to appear in your sample?

The opening star has eight people. One person has seven connections; each of the others has one. What changes when we enter through a connection instead of choosing a person?

Keep a first thought

Optional. Included only when you explicitly save; excluded from shared links.

Constructed data · every relationship and outcome is supplied.

02 / OPEN THE MODEL

Edit people and connections

An undirected connection counts once. Applying a valid draft updates the model. Removing a person also removes their connections.

People · 1–20 unique IDs
Connections · maximum 60
ABCDEFGH
Highlighted lines show connections to the selected person. Equal-sized nodes, equal-width connections. Positions are a drawing choice. The numbers come from the connection list.

CHANCE OF SELECTING EACH PERSON

One person, uniformly selected. Bars use a 0–100% scale.

A1/8
B1/8
C1/8
D1/8
E1/8
F1/8
G1/8
H1/8
1.75Uniform person meanconnections
4Uniform edge-end meanconnections
7Undirected connectionsedges

Follow the idea.

A concept, in three frames

Keep the network.

Connections and people stay fixed.

Change the entry point.

A person and an edge-end are different samples.

Compare the weights.

More connections create more ways to be reached.

HOLD ONE VERSION STILL

What changes when you change the model?

Keep the current inputs beside your next adjustment.

The way you sample changes the world you see.

Choosing a person uniformly gives everyone equal weight. Choosing an edge uniformly, then one of its ends uniformly, weights each person by their number of connections.

Read the investigation →
Save this experiment

Saved only in this browser. Clearing browser data removes local copies; export a copy from your notebook to keep it.

MODEL & LIMITS

What this model leaves open

These are two exact sampling procedures on a supplied graph. They do not show that every person has fewer connections than their contacts, or measure friendship quality.

  1. InputsWhat is supplied?
  2. DefinitionWhat is counted?
  3. InferenceWhat follows?
Inspect the exact workings

Sum of degrees = 14 = 2 × 7 edges. Sum of squared degrees = 56. Person mean = 14/8 = 1.75. Endpoint mean = 56/14 = 4.

Every person, connection and sampling weight
PersonNeighborsDegreePerson weightEdge-end weight
AB, C, D, E, F, G, H71/87/14
BA11/81/14
CA11/81/14
DA11/81/14
EA11/81/14
FA11/81/14
GA11/81/14
HA11/81/14

Connections: A—B, A—C, A—D, A—E, A—F, A—G, A—H. For a nonempty edge set, the two means differ by degree variance divided by mean degree. Equality holds when every person has the same degree.

Assumptions, sources and evidence status

Original constructed fixture: constructed-networks-v1. networks-v1. No empirical observations are represented by these example counts.

  • Uniform edge-end sampling is not uniform-person-then-neighbor sampling.
  • An edgeless graph has no endpoint sampling distribution; its endpoint mean is undefined.
  • Degree is not worth, friendship quality or proof that every person has fewer connections than their contacts.
Read the definition and primary background sources →