2022 Introduction to Statistics in Research Mitchell 2nd ed

I N T R O T O R E S E A R C H : D A T A V I S U A L I Z A T I O N & C O M M O N S T A T T E S T S

Nuts and Bolts of Statistics – Part 2 (with updates!)

Statistics is a scientific process, but there is an art to it. Our overall goal of statistics is to learn from the data and be able to communicate what we find. Every statistical investigation begins with a question. For example,

"Is the new BASE tool used to discharge our patients effective in lessening readmits?"

or

"Is the drug we've developed for COVID-19 effective?"

You may think you know the answer. So what's the next step? The next step is probably a SAMPLE, but what kind and how do we plan to collect the data? Nuts and Bolts 1covered some sampling methods, but let’s dig a little deeper into types of variables.

Working with variables Variables are any characteristic whose value may change from one individual to another.

Data is the values for a variable from individual observations. (Quiz)

Example of Univariate data: The SMWC Basketball coach records the height of each student in his class. Thus an observation of a single variable made on individuals in a sample or population.

Example of Bivariate data: The SMWC Basketball coach records the height and weight of each student in his class. Thus bivariate data consist of a pair of numbers from two variables for each individual in a sample or population.

Example of multivariate data: The SMWC Basketball coach records height, weight, and a number of sit-ups. You start to see the pattern, right?

There are TWO types of variables (and this is important for statistical software). They are categorical and numerical. You can always make sure you define it correctly if you apply the math test. The "math test" is just asking yourself if it makes sense to find an average.

For example, you have codes to your combination lock. Is this categorical or numerical? Does it make sense to find an average code to combination locks?

NO! So, codes to combination locks are categorical and not numerical.

Table 61- Types of Variables

Discrete numerical: Isolated points along a number line. Usually counts of items (like the number of textbooks purchased).

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