Chapter 10 Flashcards
(38 cards)
Statistics
When indices are calculated for a sample drawn from the population
Descriptive statistics
Permit researchers to describe the information contained in many, many scores with just a few indices such as the mean and median.
Parameters
When indices are calculated from the entire population
Quantitative data
A team when the variable being studied is measured along a scale that indicates how much of the variable present. Quantitative data are reported in terms of scores
Categorical data
Indicate the total number of objects, individuals, or events the researcher finds in a particular category
Raw score
The initial score obtained
Derived scores
When raw scores are taken and converted into more useful scores on some type of standardized basis
Age equivalent scores and grade equivalent scores
Tell what age or grade and individual score is typical
Percentile rank
Refers to the percentage of individuals going at or below given raw score. Percentile ranks are sometimes referred to as percentiles, although this term is not quite correct as a synonym.
PR = [(Number of students below score + All students all score) / Total number in group] x 100
Standardized scores
Indicate how far a given raw score is from a reference point
Frequency distribution
Done by listing the scores in re order from high to low, with tallies to indicate the number of subjects receiving a score
Grouped frequency distribution
Scores in the distribution are grouped intervals
Steps involved in constructing a frequency polygon
Numbered from 1 to 5 on page 191
Positively Skewed polygons
The tale of the distribution trails off to the right direction of the higher more positive score values
Negatively skewed polygons
The longer tail of the distribution goes off to the left
Histogram
A bar graph used to display quantitative data at the interval or ratio level of measurement
Stem leaf plot
A display that organizes a set of data to show both its shape and its distribution
Normal distribution
When a distribution curve is normal, the large majority of the scores of concentrated in the middle of the distribution, and the scores decreasing frequency the farther away from the middle they are
Three most common used averages
Mode
Median
Mean
Mode
The most frequent score in a distribution. The score obtained by more students than any other score
Median
The point below and above which 50% the scores in a distribution fall. In short the midpoint
Mean
Another average of all the scores in the distribution. Determined by adding up all the scores and then dividing this by the total number of scores
Quartiles
Page 198
Five number summary
Consists of the lowest score, the median, and the highest score.
