Earning Power

Appendix C—Sampling Methodology
PMI’s Earning Power: Project Management Salary Survey, Ninth Edition, was sent to a stratified sampling of customers
from 34 different countries. Countries included in the sampling were selected based on two factors: concentration of
PMI members within a given country and the desire to represent all regions of the globe.
The survey invitation was sent via an email that included a link to the web-based survey. Using a web-based survey
benefited the research in several ways, including the ability to survey a large number of respondents at a relatively low
cost (as compared to other data collection methods), a condensed data collection time period and a fairly high
response rate.
PMI contracted with a third-party market research vendor, Quantum Performance Solutions (QPS), for this project. QPS
used its PeriscopeIQ web survey technology platform (www.periscopeiq.com) to conduct this research. QPS is a global
strategy consulting and market research firm with a focus on scientific rigor and research-based methodologies. The
salary survey was conducted according to QPS's best compensation survey practices, including confidentiality of
individual responses.
The first email invitation to the web-based survey was sent to 209,834 professionals on 4 March 2015. Non-responders
were sent a total of three reminder emails throughout the four-week field period, which ended on 6 April 2015. Data
collection for the survey closed with a total of 36,501 completed surveys, yielding a response rate of 17%.
The data collected were run through extensive quality checks by QPS, resulting in the elimination of 10,154 cases
based on the following criteria:
Reason
Number deleted
Not full-time 2,693
Selected “poor fit” for job position 759
Selected undefined country 545
Analyzed to be an anomaly 520
Analyzed to be an outlier or violated other best
2,531
compensation practice principles
Excluded job titles 3,106
As shown in the table above, 759 respondents were eliminated from the data because they noted that the position descriptions
provided did not adequately represent their current job responsibilities. These 759 respondents represent only 2.1% of the total
respondent population, which indicates that the position descriptions provided in the survey are fairly accurate and widely
used.
As a result of this data cleaning process, a total of 26,347 respondents were included in the full report.
Due to the fact that a stratified sampling methodology was used rather than a random sampling, data are not reported
in aggregate form (all countries combined together) in this report. Therefore, we have not calculated an overall
sample error for the entire sample, but have instead included sample error estimates for each country in the table
below.
Earning Power: Project Management Salary Survey, Ninth Edition
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