The analysis of the data from a study indicates that there was a significant difference between the two groups, which were randomly selected and composed of 100 subjects each

Question

The instruments measuring stress, mood, and various scaled measures of emotion were well normed, widely tested, and suitable. As the researcher begins interpretation of the data, she discovers that during data collection one of her assistants had recorded the demographic item "household size" incorrectly, understanding the item as "number of people who live with you." The original paper surveys are still available, and the ones this particular assistant collected are all clearly marked with her initial on each page. How can this data item be "saved"? (Select all that apply.)
a. Erroneous values can be identified and eliminated from the data analysis for this single item.
b. Erroneous values can be located and re-entered as the true values, since the systematic error has been identified, quantified, and attributed.
c. Data analysis may proceed and the error noted in the final report as a methodological limitation.
d. An overlapping ordinal measurement can be used, in which the categories are 0-1, 1-2, 2-3, and so forth.
e. The data may be analyzed as a nominal variable and so coded.

Answer 1

ANS: A, B
Many activities that occur during data collection affect the meaning of study results. Methodological limitations result from factors such as nonrepresentative samples, weak designs, single setting, limited control over treatment (intervention) implementation, instruments with limited reliability and validity, limited control over data collection, and improper use of statistical analyses. Nominal level of measurement is the lowest of the four measurement levels or categories. It is used when data can be organized into categories of a defined property but the categories cannot be ordered. Data that can be measured at the ordinal level can be assigned to categories of an attribute that can be ranked. In interval level of measurement, distances between intervals of the scale are numerically equal. Interval scales are assumed to be a continuum of values. Ratio level of measurement is the highest form of measure and meets all the rules of the lower forms of measures. To be meaningful, measurements must be mutually exclusive. Changing the data to a nominal or ordinal measurement will not "save" the item. Reporting the item as erroneous does not "save" the item.