Basic Concepts Basic Concepts Qualitative Quantitative Dimensional Categorical

Basic Concepts

Basic Concepts Qualitative Quantitative Dimensional Categorical

Basic Concepts § Scales of Measurement: § Nominal § labeling/classifying objects § i. e. your last name, names on jerseys, social security number, etc. § not technically a scale of measurement since nothing is measured § Ordinal § labels that imply rank § i. e. place in a race, military rank – 1 st > 2 nd > 3 rd and General > Lieutenant > Private § doesn’t say how much more one is than the other

Basic Concepts § Interval § provides labels that imply exactly how much different one label is than another § i. e. temperature - 15° F is 5 ° F more than 10 ° F § lacks true zero point - 0 ° F does not represent the complete absence of heat because we have negative values of °F § Ratio § has all of the above, plus a true zero point § i. e. height, weight, ° Kelvin – 0 lbs represents a true lack of weight § can talk about 16 ° being four times 4 °, which is a proportion /ratio, hence the name of the scale - x = 4 y § often very difficult to identify in practice if a true zero point exists

Basic Concepts § Scales of Measurement § Nominal § Qualitative § Ordinal § Interval § Ratio § Quantitative

Basic Concepts § Variables § Discrete versus Continuous Variables § same as Categorical versus Dimensional variables § Not to be confused with “discreet” variables, that people simply do not think should be talked about

Basic Concepts Constant Variable Qualitative Quantitative Categorical/ Discrete Nominal Ordinal Dimensional/ Continuous Interval Ratio

Basic Concepts § Variables versus Constants § A constant has only one possible value that it can assume § π = 3. 1415923536… § A variable can assume many possible values § X=? § Independent Variables (IV’s) versus Dependent Variables (DV’s) § IV manipulated, DV measured § Whether a variable is a DV or IV depends upon the design of the experiment

Basic Concepts § Variables § In true experiments, the effects of one variable (the IV) are manipulated to see the effects on another variable (the DV) § All other factors other than the IV are kept constant so that we can attribute the change to the IV and not to something else § Example: Influence of direct heat on the temperature of water § IV = presence or absence of heat § DV = temperature of water

Basic Concepts § Mathematical Notation § X - add everything that is an “X” §Y 5 Y = 5 + 10 + 7 +3 + 5 = 30 10 7 3 5

Basic Concepts §X 10 15 12 9 10 56 Y 3 4 1 1 3 12 X 2 100 225 144 81 100 650 X-Y 7 11 11 8 7 44 XY 30 60 12 9 30 141

Basic Concepts § Mathematical Notation § PEMDAS – Parenthesis, Exponents, Multiplication, Division, Addition/Subtraction § ( X)2 ≠ X 2 § XY ≠ [( X) x ( Y)] § However, (X – Y) = X - Y