Module 15: Data Organization, Central Tendency, and Variance Flashcards
Frequency distribution
a table in which all of the scores are listed along with the frequency with which each occurs
Relative frequency
can be multiplied by 100 to get a percentage
Class interval frequency distribution
can be created for larger data sets. we combine individual scores into categories, or intervals, and list them along with the frequency of scores in each interval.
Graphs
Sometimes a picture is of greater value than frequency distributions. The most common graphs used are:
- Bar graph
- Histogram
- Frequency polygons
Bar graph
a graphical representation of a frequency distribution in which vertical bars are centered above each category along the x-axis and are separated from each other by a space, which indicates that the levels of the variable represent distinct, unrelated categories.
Qualitative variable
a categorical variable for which each value represents a discrete category
Statistics
refers to a range of techniques and procedures for analyzing, interpreting, displaying, and making decisions based on data.
Histogram
a graphical representation of a frequency distribution in which vertical bars are centered above scores on the x-axis, but in a histogram the bars touch each other to indicate that the scores on the variable represent related, increasing values. A histogram is more useful when the data collected are on an ordinal, interval or ratio
scale
Quantitative variable
the scores represent a change in quantity
Frequency polygons
a line graph of the frequencies of individual scores, this is a type of histogram. Frequency polygons are appropriate when the variable is quantitative or the data are ordinal, interval, or ratio. In this respect frequency polygons are similar to histograms. They are especially useful for continuous data (such as age, weight, or time) in which it is theoretically possible for values to fall anywhere along the continuum.
Descriptive statistics
Are numerical measures that describe a distribution by providing information on:
- central tendency
- width
- shape
Inferential statistics
generalizing from observed data to a statistical population: all the data that could have been observed.
Hypothesis testing
what conclusions do the data permit considering statistical hypotheses about the population?
Estimation
what do the data suggest about plausible values in the population?
P-value
the probability of obtaining the sample results or even more extreme results under the assumption that the null-hypothesis is true.