Nominal
Attaches numbers to categories, you can only tell how many, mutually exclusive and can only fit into one category. (i.e., race, religion, birthplace.)
Ordinal
(Order, rank), gives us a gross ranking where quantity is relative. Discrete variable. (i.e., we can tell that A has more than B, but not by how much.)
Interval
Measures quantities in equal intervals between units, can be said to have magnitude because they are based on a common unit of measurement. (i.e., pain scales). We know the count, rank order and quantity. No 0 in interval level of measurement.
Ratio
Also measures quantity at equal intervals between units, but includes an absolute zero. (i.e., Weight or height).
What type of level of measurement (LOM) is student status (full or part time)?
Nominal.
What type of LOM is the CES-D Depression Scale?
Interval.
What type of LOM is attendance (# of classes missed)?
Ratio.
What type of LOM is years in school (First, Sop, Jr, Sr)?
Ordinal.
What type of LOM is zip code (85004, 85285)?
Nominal.
What type of LOM are academic degrees (BA, MA, PhD)?
Ordinal.
What type of LOM is temperature?
Interval.
What type of LOM is a suit of cards (Spades, hearts, diamonds)?
Nominal.
What type of LOM is levels of stress (10 low to 20 high)?
Interval.
What type of LOM is calories consumed in a day?
Ratio.
Why is knowing the level of measurement important?
It determines what statistical testing you can do.
What are relative frequencies?
f1/n (%), refer to the number of variables in a question, to the total number. (i.e., 6 PhD students/17 total or 35%).
What are ratios?
f1:f2, frequency of the fire value compared with the frequency of a second value (i.e., ratio of blue squares to orange circles, 3:6 or 1:2).
What is the Mode (Mo)?
The most frequently occurring score. (i.e., shoe size statistic).
What is the Median (Md)?
Score of value which cuts the distribution in half, such that half of the scores fall above the median and half the scores fall below. The exact center of a distribution.
How do you calculate the median of a odd number of observations?
Add 1 and divide by 2, i.e., 15+1=6/2=8th observation.
What is the Mean (X or M)?
The arithmetic average, this is sensitive to extreme scores.
What is the difference between mean and median?
Mean uses all the data, has desirable statistical properties, affected by extreme high or low values (outliers), and may not be best characterized by skewed distributions. Median is not affected by outliers, may better characterize skewed distributions.
Range (R)
The difference between the highest and lowest scores, a one number summary. (i.e., 50 - 13 = 37). Very sensitive to extreme values.
Standard Deviation (SD)
Tells us how widely dispersed the scores are, "typical deviation within a sample", it indicates how far all scores vary from the mean.
Variance
Another indication of how far all of the scores vary from the mean. This is equal to the square of the SD.
What is the difference between variance versus standard deviation?
Standard deviation uses the same units as a variable, more readily interpreted, is a measure of absolute deviation. Variance has properties making it useful for certain statistical analysis.
What are the cornerstones of the normal curve?
Mean and standard deviation.
What are the five main characteristics of the normal curve?
1. Unimodal: the mean, median and mode all rest at the center point, 2. Symmetric - what is on the left is identical to what is on the right, 3. The abscissa is asymptotic to the axis: the tails go on to infinity and never touch the line, 4. 68% of all th
What is it called when a normal distribution has the exact same mean, but a different standard deviation?
A family of distributions due to a difference in shape.