sigmoid curve

Meanings

1. 1nouncountable

   A curve shaped like the letter S, often used to show slow growth at first, then fast growth, then slow growth again.

   Grammar: It is a countable noun phrase, so you can say 'a sigmoid curve' or 'sigmoid curves'.

   Patterns

   • a sigmoid curve
   • the sigmoid curve
   • fit a sigmoid curve to something

   The graph shows a sigmoid curve, with a gentle start and a steep middle section.

   In biology, population growth often follows a sigmoid curve.

   The data points fit a sigmoid curve better than a straight line.

2. 2nouncountabletechnicalmathematics

   In statistics, a curve representing the logistic function, used to model probabilities between 0 and 1.

   Grammar: Also called a 'logistic curve' in this sense.

   Patterns

   • the sigmoid curve
   • a sigmoid curve model

   The logistic regression model produces a sigmoid curve.

   Machine learning often uses a sigmoid curve to map values to probabilities.

Word forms

Common combinations

fit a sigmoid curve

We can fit a sigmoid curve to the experimental data.

sigmoid curve shape

The sigmoid curve shape is typical of many growth processes.

follow a sigmoid curve

The sales figures follow a sigmoid curve over the product's life cycle.

Synonyms and how they differ

S-curve

A more general term for any curve shaped like an S; 'sigmoid curve' is more technical and often used in mathematics and biology.

logistic curve

Specifically refers to the sigmoid curve of the logistic function; use this in statistics.

Word family

sigmoid adjective

Shaped like the letter S or the Greek letter sigma.

Commonly confused: sigmoid curve or sigmoid colon?

Practice

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