Best practices for statistics
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Best Practices for Statistics. Best Practices. Purpose of Statistics. Best Practice: Know what you already know, what you want to know and what you don’t know. Starting with Your Research Question.

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Best Practices for Statistics

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Best Practices for Statistics


Best Practices


Purpose of Statistics


Best Practice:Know what you already know, what you want to know and what you don’t know


Starting with Your Research Question

How do users differ when (searching, finding, selecting) (articles, books, Web sites)?

What are factors associated with ___________?

What are the effects of ___________On ____________?

Which is better at improving _________?

How are people (finding, selecting, using) _______?


Kinds of Variables


Levels of Measurement (NOIR)


Another Way


Likert-Type Scale?


Best Practice:Have a Comparison Group


Ways of comparing…


Kinds of Comparison


Best Practice: Use a Valid Measure


Validity of Measures

Are you actually measuring what you are trying to measure?


Use a tool with established validity

User Engagement Scale (UES)

Approaches and Study Skills Inventory for Students (ASSIST)


Establish Validity of Measures


Best Practice: Have a Data Plan


Goal of Data Collection in Statistics


Bias

Systematic (not random) deviation from the true value (Statistics.com)


Data Input

Have a data entry plan

Train the inputters

Use data validation tricks

Double-entry


Best Practice:Get to know your data


Exploratory Data Analysis


Measures of Central Tendency


Spread & Distribution


Distribution or Spread of Qualitative Data


Pivot Tables in Excel


Demonstration of Pivot Tables for Spread of Qualitative Data


Graph & Chart Rules of Thumb


Quantitative Distributions


Exploratory Data Analysis

  • John W. Tukey

  • Exploratory Data Analysis

  • Examining your data visually.

    • Stem & Leaf

    • Hinges

    • Box plots

    • Scatter plots, etc.


Stem-and-Leaf

First digit(s)

Last digit


From Stem-and-Leaf to Histograms


Histograms in Excel


Demonstration of Histogram in Excel


Spread of Quantitative Data

How variable is the data?


Range & Quartiles


Presentation of Spread

  • Box plots

    • Median

    • Upper & lower quartiles

    • Outliers


Standard Deviation

  • Measure of dispersion of data

  • Square root of the average variation from the mean


What does the SD tell you?


Spread in Excel


Normal Distribution


Skewed Distributions


Demonstration of distributions

Distribution of the Population

The “Truth”

N is the # of samples

n is the number of items in each sample

Watch the cumulative mean & medians slowly merge to the population


Best Practice:If it doesn’t fit, change it

Transformation of data


Why Transform?


How Transformation Works


How to Become Normal

  • Express the result in the terms of the transformation


Best Practice: Place your bets before you start


Inferential Statistics


Hypothesis Testing


Example Hypothesis

UNT Libraries provides access to…

*…of journal articles cited by UNT PACS faculty in journal articles published between 2008-2011.


Hypothesis Testing


Testing Hypotheses


Best Practice:Choose the Best Method for your Question and Data


Know the tests


Factors associated with choice of statistical method


Use a Flow Chart


Best Practice: Going Beyond the p-value


And the p-value says…


More Useful Statistics


Effect Sizes of Quantitative Data


Effect Sizes of Qualitative Data


Confidence Intervals


Statistical Analysis


Best Practices


Resources


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