Variables 2018 Year - 2 Levels Listed 2019 Levels Proportions 0.3933 0.6067 Number of Observations 70 108 Total Observations 178 SALT should summarize three numerical variables in the "Numerical Variables" table and three categorical variables in the "Categorical Variables" table on the right side of this page. The easiest measure of center to compute is the mode. The mode of a dataset is the observation that occurs most frequently. A dataset can have more than one mode if more than one observation ties with the most frequent occurrences. A dataset can also have no mode. Scanning the Categorical Variables Summary Table on the Descriptive Statistics page we can find how frequent the year values are for the year variable. Fill in the missing values in the summary table below. Variables Levels Numbers of Observations 2018 70 Year - 2 Levels Listed 2019 108 The Year variable has a mode of 178 x because there were more school days observed during this year of the 2018-2019 New York City school year.