by adding a “no response” for missing data) and once with these samples dropped. In this case, either another remedy should be employed or the analysis should be run twice: once with samples with missing data retained (e.g. If the frequency of the responses to question 7 changes significantly when samples that are missing responses to question 5 are dropped, then the missing data is not random, and so dropping samples can bias the results of the analysis. suppose a lot of people didn’t answer question 5 but everyone answered question 7. Of particular importance is the randomness of the missing data. questions) that measure similar aspects of the characteristics being studied. a particular question in the case of a questionnaire or survey) that has a high incidence of missing data, especially if there are other variables (e.g.
These are characteristics that might be quite relevant to the analysis. people filling out a long questionnaire may give up at some point and not answer any further questions, or they may be offended or embarrassed by a particular question and choose not to answer it. if a questionnaire with 5 questions is randomly missing 10% of the data, then on average about 41% of the sample will have at least one question missing.Īlso, it is often the case that the missing data is not randomly distributed. This problem is bigger than might first be evident. In this case, additional sample data elements may need to be collected.
This is particularly relevant when the reduced sample size is too small to obtain significant results in the analysis.
One problem with this approach is that the sample size will be reduced.
#How to use data analysis in excel for non numerical value how to
In Identifying Outliers and Missing Data we show how to identify missing data using a data analysis tool provided in the Real Statistics Resource Pack.Ī simple approach for dealing with missing data is to throw out all the data for any sample missing one or more data elements. For example, in conducting a survey with ten questions, perhaps some of the people who take the survey don’t answer all ten questions. One problem faced when collecting data is that some of the data may be missing.
0 kommentar(er)
