Moz's 2015 Search Engine Ranking Factors presents survey data from over 150 marketing professionals specializing in Search Engine Optimization. Their answers provide insight into the inner workings of the search marketing both now and in the future. The following data represents the opinions of our respondents of the various weighting of factors thought to be used (or not used) in Google's search algorithm.

Google's Broad Search Ranking Algorithm

Our respondents rated the relative levels of influence exerted by broad areas of ranking factors on a scale of 1 (not influential) to 10 (highly influential).

Definitions:

Domain-Level, Keyword-Agnostic Features: Domain name length, TLD extension, SSL certificate, etc.

Domain-Level, Link Authority Features: Based on link/citation metrics such as quantity of links, trust, domain-level PageRank, etc.

Domain-Level Keyword Usage: Exact-match keyword domains, partial-keyword matches, etc.

Domain-Level Brand Metrics: Offline usage of brand/domain name, mentions of brand/domain in news/media/press, toolbar/browser data of usage about the site, entity association, etc.

Page-Level Social Metrics: Quantity/quality of tweeted links, Facebook shares, Google +1s, etc. to the page

Page-Level Link Metrics: PageRank, Trust metrics, quantity of linking root domains, links, anchor text distribution, quality/spamminess of linking sources, etc.

Page-Level Keyword & Content-Based Metrics: Content relevance scoring, on-page optimization of keyword usage, topic-modeling algorithm scores on content, content quantity/quality/relevance, etc.

User Usage & Traffic/Query: Data SERP engagement metrics, clickstream data, Visitor traffic/usage signals, quantity/diversity/CTR of queries, both on the domain and page level

Page-Level, Keyword-Agnostic Features: Content length, readability, Open Graph markup, uniqueness, load speed, structured data markup, HTTPS, etc.

Page-Level Keyword Usage Features

These features describe use of the keyword term/phrase in particular parts of the HTML code on the page (title element, H1s, alt attributes, etc).

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Page-Level Keyword Agnostic Features

These elements describe non-keyword-usage, non-link-metrics features of individual pages (such as length of the page, load speed, etc.).

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Page-Level Link-Based Features

These features describe link metrics to the individual ranking page (such as number of links, PageRank, etc.)

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Page-Level Social Metrics

These features relate to third-party metrics from social media sources (Facebook, Twitter, Google+, etc.) for the ranking page.

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Domain-Level Keyword Usage Features

These features cover how keywords are used in the root or subdomain name, and how much impact this might have on search engine rankings.

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Domain-Level Brand Metrics

These features describe elements that indicate qualities of branding and brand metrics.

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Domain-Level Link-Authority Features

These features describe link metrics about the domain hosting the page.

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Domain-Level Keyword-Agnostic Features

These features relate to the entire root domain, but don't directly describe link or keyword-based elements. Instead, they relate to things like the length of the domain name in characters.

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

Negative Ranking Factors

These responses relate to the relative negative impact of various features in Google's ranking algorithm.

Rated on a scale from 1 (no direct influence) to 10 (strong influence).

The Future of Search

Respondents were asked to predict how the following factors might change (in terms of their direct impact on Google's ranking algorithm) over the next 12 months.