Ex 1 Flashcards
Mutually Exclusive variable
A type of variable that permits each case to be counted in one and only one category
Exhaustive Variable
Meaning a category is provided for each possible category
Independent Variable
A variable that is identified as a casual variable. Thought to cause the dependent variable
Dependent Variable
The variable that is effected, resultant, or the outcoem. It is caused by the independent variable
Three Levels of Measurement
Represented by nominal, ordinal, and interval-ratio variables
Nominal Variable
Variables at this level have categoies that are not numerical. They incldue gender, zip code, race, religion. Lowest level of measurement. Only comparison permited is that of category size
Ordinal Variable
- More sophisticated than nominal
- Scores or categories that can be ranked from high to low
- We can say cases are higher or lower
- upper, middle, working, lower
Interval Ratio Variable
These variables provide distances between ranks, quantitative.
- Measured in units that have equal intervals.
- Have true zero point
- Age, number of children, income
Descriptive Statistics
Statistic techniques to organize and describe data from sample/ population
- Measure of central tendency
- measure of tendency
Inferential Statistics
Make predictions based upon data from sample
Poppulation
The total colelction of all cases in which the researcher is interested and wishes to understand better
-All possible cases
Sample
A carefully chosen subset of a population. In inferential stats, information is gathered from a sample and then generalized to a population
Sample statistics
What we find in a sample
Cumulative frequency
In frequency distribution that displays the number of cases within an interval and all preceding intervals
Cumulative percentage
In frequency distribution displays percentage of cases within an interval and all preceding intervals
Frequnecy distribution
A table that displays the number of cases in each category of a variable
Rate
The number of actual occurances of some phenomenon or trait divided by the number of possible occurrence per some unit of time
- Cases / time
Pie chart
Usually used to display percentage of cases in each category of a variable
- For nominal or ordinal variables
Bar chart
A graphic display device for nominal or ordinal variables with few categories.
Histogram
A graphic display device for interval ratio variables. Classes are represented by contiguous bars of equal width
-borders of bars touch
mean
The arithmetic average of the scores
- bar over x
Median
The point in a distribution of scores above and below which half of the cases fall
- Exact middle point
Mode
The most common value in distribution or largest category
- Most common
Standard Deviation
- Average distance from the mean
- interval ratio
- it tries to estimate the amount of diversity in certain things that are interval ratio in nature such as income, age, education in years
Variance
The amount of difference
- Average of squared deviation from mean
Range
The highest score minus the lowest score
interquartile range
The distance between the upper and lower quartiles
= Q3 - Q1
IQV
Index of Qualitative Variation
- its a measure of variation for categorical variables
- A way to measure the variability of nominal variables
- It is the total differenes divided by the total number of possible differences
- It is always between zero and one
- 0 == lack of variation
- 1 == complete variation
- We use single number to tell how much variation observed
- Fails to take into consideration all points because it only looks at the squared percentages
Z Scores
Number of standard deviation that a given raw score is above or below the mean
-Z == below mean
Z+ == above mean
Standard Normal Distribution
A normal distribution represented in standard z scores
Inferential Statistics - big picture
Prediction about population from observations from a sample
- Probablilty technique provides best opp for representable sample of pop
