EBI Statistics 101

Survey Questions There are three basic types of questions used within an EBI survey: Categorical Scaled Text

Categorical Question Allows the data to be divided into groups Example: gender or race Often referred to as a “demographic question” A categorical question allows respondents to place themselves into exactly one category A demographic categorical question characterizes the respondent’s personal attributes A demographic question is a type of categorical question

Scaled Questions Allow respondents to indicate how strongly they feel about a question or statement using a rating scale Good for gauging the respondent’s attitude Example:

Text Question Is considered “open-ended” Allows respondents to write an answer in their own words Example:

Basic Statistical Terms Mean response Standard deviation Frequency distribution Factor means

Mean Response Is an average Is only used on scaled questions Is computed by taking the sum of all the numerical responses to a question and dividing that sum by the number of people who answered the question N/A (not applicable) responses are omitted from the mean

Standard Deviation Tells how tightly the responses are clustered around the mean; a measure of dispersal, or variation, in the responses Responses are clustered near the mean Responses are dispersed from the mean

Standard Deviation If the responses are close to the mean, we expect to see a low standard deviation. This shows the respondents answered the question in a similar manner. In contrast, if the responses are spread across a greater range, the standard deviation will be higher.

Standard Deviation Higher standard deviation is often interpreted as higher volatility, because more respondents answered one extreme or the other. In comparison, lower standard deviation would likely be an indicator of stability. The most consistent responses are those with the lowest standard deviation.

Frequency Distribution Shows the number or percent of individuals that selected each of the responses for the corresponding question N shows the number of people who responded Key Text shows the answers to the question

Frequency Distribution Frequency distributions can also be formed by grouping responses together.

Frequency Distribution If each category represents an equal portion of the participants, it indicates there is little agreement among the participants. If one category represents a large portion of the participants, then there is a large degree of agreement among the participants. This reflects a common level of satisfaction.

Factors A group of questions statistically tied together A factor describes a broad concept more accurately than a single question does Dining Services Factor How satisfied are you with the following aspects of the dining services? Food quality Cleanliness Atmosphere Hours

Dependent and Independent Factors Overall program effectiveness or overall satisfaction is typically the dependent factor The remaining factors are typically the independent factors

Regression A statistical method used to predict the value of the dependent variable (typically the “Overall Program Effectiveness” factor) by studying its relationship with the independent variables (typically all other factors) Tells us the level of impact the independent factors have on the overall factor

Statistical Testing Suppose you examined the mean response to a question asked of male and female participants. In all likelihood, the mean for males will be different than the mean for females. Statistical testing reveals whether the difference occurred as the result of random chance, or if there is a real difference between the way men and women perceive the question.

Statistical Testing Categorical – tests for a real difference in the mean of two categories Example: men vs. women Longitudinal – tests for a real difference in the mean from one year to the next Example: 2009 vs. 2010 External – tests for a real difference in the means of your institution and comparison institutions Example: your institution vs. select 6

Benchmarking An improvement process in which an institution compares its performance against other institutions and uses the information to improve its own performance Two types of benchmarking- internal external

Internal Benchmarking Longitudinal – shows where you have made improvements and where improvements could be made Unit/Category – shows which units or categories performed at a higher level

External Benchmarking Select 6 – compares your institution to six participating peer institutions of your choice Carnegie Class – compares your institution to a group of similar institutions All Institutions – compares your institution to all other participating institutions combined

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