Statistics Flashcards
The science of assembling, classifying, tabulating, and analyzing data of a numerical nature to present significant information about a given subject.
Statistics
Population
An entire group of observations that have at least one characteristic in common
A representative group of elements selected from the total population.
Sample
Parameter
A characteristic of a population
Statistic
A characteristic of a sample
A collection of discrete information (numbers, scores, measurements)
Data
Qualitative Data versus Quantitative Data
Qualitative- Non-numeric data
Quantitative- Numeric data
Assigning numbers to observations according to pre-set rules
Measurement
Variable
A measured characteristic that can have various values or levels
Discrete variables
Have only certain values (whole numbers)
Continuous variables
Can have any value (whole numbers, decimals, fractions)
A way of summarizing data from samples, i.e. tables and graphs
Descriptive statistics
Three ways to summarize data
tabular, graphical, numerical
Tabular
Frequency Distribution
Cumulative Frequency Distribution
Grouped Frequency Distribution
Cumulative Grouped Frequency Distribution
Graphical
Graphs from Frequency Distribution
Frequency Histogram
Bar Graph
Frequency Polygon
Numerical
Measures of Central Tendency
Measures of Variability
What does “N” represent?
Total frequency for the distribution
What is cumulative frequency?
Frequency of the scores including the frequency of the previous scores (i.e. a running tally)
What is grouped frequency distribution?
When data has more than 20 scores, the frequency distribution would not summarize the data much, need to group it.
Which axis is referred to as the abscissa of the graph or the category axis?
X-axis
Which axis is referred to as the ordinate or the value axis?
Y-axis
How is a histogram similar to a bar graph?
A histogram is similar to a bar graph but is used to represent data at the ratio or interval data, while the bar graph is used to represent nominal or ordinal data.
T/F: A histogram has gaps in between the bars.
False, no gaps
Bar graph
A bar graph is used to represent nominal or ordinal data. The bars are separated by a space.
Frequency polygon
A frequency polygon is a curve. It can be created with intervals.
What are the measures of central tendency?
Mean, median, mode
Median
The middle value of a data set.
Mode
The most frequent value in the data set.
Mean
The average of the data set.
Population mean
N
Sample mean
n
Measures of variability
Range, variance, standard deviation
Range
The range is the difference between the highest data value and the lowest value plus 1 for whole number data.
Range = (highest value – lowest value) + 1
Variance
The average squared deviation of the scores from the mean.
Population variance
Sigma squared
Sample variance
S squared
T/F: The formula for the variance by the raw score method is mathematically equivalent to the deviation score method.
True
How is raw score method different?
Don’t include the mean
