- published: 29 Jul 2017
- views: 1503
In statistics, missing data, or missing values, occur when no data value is stored for the variable in an observation. Missing data are a common occurrence and can have a significant effect on the conclusions that can be drawn from the data.
Missing data can occur because of nonresponse: no information is provided for several items or no information is provided for a whole unit. Some items are more sensitive for nonresponse than others, for example items about private subjects such as income.
Dropout is a type of missingness that occurs mostly when studying development over time. In this type of study the measurement is repeated after a certain period of time. Missingness occurs when participants drop out before the test ends and one or more measurements are missing.
Sometimes missing values are caused by the researcher—for example, when data collection is done improperly or mistakes are made in data entry. Data often are missing in research in economics, sociology, and political science because governments choose not to, or fail to, report critical statistics.
In this video I describe how to analyze the pattern of your missing data (monotone or arbitrary) and how to use common methods to deal with missing data.
This module describes how missing data can be managed while maintaining data quality. It explains how to plan for missing data; defines different types of "missingness;" outlines the benefits of documenting missing data and illustrates how to document missing data; and describes procedures to minimize missing data. Upon completion of this module, students will be able to explain why data managers should strive to minimize missing data and develop a plan to record or code why data are missing.
Most scientists carefully collect data and select data resources. In a perfect world, we would have pristine, complete datasets. Yet, we are frequently challenged by incomplete and missing data. We are often taught to "ignore" missing data. In practice, however, ignoring the wrong types of data may build biases into our datasets, invalidating our conclusions. Here, we discuss three types of missing data (data missing completely at random, missing at random, and missing not at random) and heuristics for identifying and dealing with each type. Then we delve into an example, where we impute missing data for a simulator that utilizes reinforcement learning to predict effective HIV treatments. When we finish, you will know how to identify each of the three types of missing data and how to deal ...
Software doesn't deal well with missing data, so what can be done about it? Professor Uwe Aickelin talks about whether we need to replace it. Known Unknowns: https://youtu.be/pIG3bdDj1ps How GCHQ Classify Security: https://youtu.be/iesgXoOBLZM Inside a Data Centre: https://youtu.be/fd3kSdu4W7c Machine Learning Methods: https://youtu.be/qDbpYUbf3e0 http://www.facebook.com/computerphile https://twitter.com/computer_phile This video was filmed and edited by Sean Riley. Computer Science at the University of Nottingham: http://bit.ly/nottscomputer Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com
Technique for replacing missing data using the regression method. Appropriate for data that may be missing randomly or non-randomly. Also appropriate for data that will be used in inferential analysis. Determining randomness of missing data can be confirmed with Little's MCAR Test (http://youtu.be/6ybgVTabJ6s). Resources: FAQ- http://sites.stat.psu.edu/~jls/mifaq.html Schafer, Joseph L. "Multiple imputation: a primer." Statistical methods in medical research 8.1 (1999): 3-15. Sterne, Jonathan AC, et al. "Multiple imputation for missing data in epidemiological and clinical research: potential and pitfalls." BMJ: British Medical Journal 338 (2009). McKnight, Patrick E., Katherine M. McKnight, and Aurelio Jose Figueredo. Missing data: A gentle introduction. Guilford Press, 2007. Haukoo...
Learn how to use the expectation-maximization (EM) technique in SPSS to estimate missing values . This is one of the best methods to impute missing values in SPSS.
Most datasets contain "missing values", meaning that the data is incomplete. Deciding how to handle missing values can be challenging! In this video, I'll cover all of the basics: how missing values are represented in pandas, how to locate them, and options for how to drop them or fill them in. New videos every TUESDAY and THURSDAY! Subscribe for updates: https://www.youtube.com/user/dataschool?sub_confirmation=1 Have a pandas question, or a tip for others? Please leave a comment below! Learning data science in Python? I teach online courses: http://www.dataschool.io/learn/ == RESOURCES == GitHub repository for the series: https://github.com/justmarkham/pandas-videos "read_csv" documentation: http://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_csv.html "isnull" documentat...
This video introduces basic concept in missing data imputation including mean, regression, indication and EM method of single imputation and multiple imputation.
This video demonstrates how to code missing values in SPSS. Several methods of coding missing values are reviewed for both numeric and string variables.
In this session I show you how you calculate a missing value for an indicator. Sometimes you don't have a number in between a time series. For instance you have a number for 2010 and 2012 but you don't have a number for the year 2011. You do this with interpolation. This session will teach you how to interpolate. You can use the data in a graph, in a policy research note etc. once you have interpolated it.
https://exceljet.net/tips/how-to-quickly-fill-in-missing-data An easy way to add missing values to data using a dead-simple relative formula and a few other tricks. https://exceljet.net