Definitions.pdf - Definitions u25cf Measurement Unit The...

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Definitions Measurement Unit The scale of the measurement variable Measurement Variable The type of data you are collecting Observation Unit The unit you collect data from Population of Interest The population that you hope to draw a conclusion about Sample The collection of all sampling units that were selected Statistical Population The collection of all sampling units that could be selected to be in your sample Sampling Unit The unit that is selected at random Descriptive statistics is the set of tools used to describes the data in your sample. This includes calculating quantitative descriptions (e.g., average values) and creating graphs Inferential statistics is the set of tools used to say something about the statistical population based on your sample. This includes things like confidence intervals and statistical tests. Counts are used for categorical variables and are the number of observations in your sample that fall into each category. Interquartile range uses quartiles to describe dispersion in a numerical variable. It is the difference between the 3 rd and 1 st quartiles and gives the range of the innermost 50% of a numerical sample. Mean is the average value in your sample. Median is the middle value of your sample when the values are ranked from lowest to highest. Proportions are used for categorical variables and are the share of observations in your sample that fall into each category Quartile is one quarter of your sample when the values are ranked from lowest to highest. Range is the difference between the maximum and minimum values for numerical variables, or the difference between the maximum and minimum number of counts for categorical variables. Standard deviation is the square root of the variance
Variance is the typical squared distance of the numerical values from the mean. Categorical variables are ones with qualitative levels Continuous numerical variables are numerical variables where the number can be something other than an integer Data is a particular value of the variable Discrete numerical variables are numerical variables where the number can only be an integer Nominal categorical variables are categorical variables that have unordered levels Numerical variables are ones with numeric levels Ordinal categorical variables are categorical variables that have ordered levels Variable is any measurable characteristic of an observation unit. The particular value of a variable for an observation unit is the datum. Difference calculations of effect size are Y 1 -Y 2 where Y 1 and Y 2 are the means of samples from group 1 and group 2 respectively. Effect size is the change in mean value of the response variable among groups.
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