I’ve come to the frightening conclusion that I am the decisive element in the classroom. It is my personal approach that creates the climate. It is my daily mood that makes the weather. As a teacher I possess a tremendous power to make a child’s life miserable or joyous. I can be a tool of torture or an instrument of inspiration.

Haim Ginott


  • Introduction
  • Cautions
  • Normal curves
  • Frequency distributions


This page includes notes related to educational research and statistics.

Cautions related to assessment

Research in general

Educational research

Questions to ask when evaluating educational research:

Effect size

Effect size - are often expressed as standard deviations .2 means 20% of a standard deviation 

add calculation examples


Cost-effectiveness can be determined by combining effect size or impact of the intervention with the cost per student of the intervention.  Suppose the following values:

Compare with

When comparing these two. The ES of .35 is more effective than .20ES. However, .22 is less cost effective than .74

Maybe an example of tutoring or use of computer assisted instruction to improve test scores.


Normal curves,
With representations for:
standard deviation, z scores, stanines, percentiles, SAT scores, ACT scores, & IQ

IQ scores | standard deviation | percentile

standard deviation chart

Normal curve | standard deviation | z scores | stanines | percentiles | SAT | ACT | IQ |

normal curve graph

Normal curve | cummulative percentages | quartiles | percent in stanines |

normal curve


Frequency distribution examples with charts and graphs; Central tendency; Percentiles; and Correlations

History Midterm for fifty students - scores and frequency distributions

score set image

one score range image

example 2 magnitude table

example 2 distribution table image


Army General Test Scores of 100 adults selected randomly

scores Image

example 2 histogram image

frequency polygon image

graph representation 3 image


graph distribution image


graph distribution 2 image


Distribution for Percentage and Percentile Rank example

frequency distribution percentage image

Central Tendency

central tendency skewed images

skewed percentile images

variability image



scatter diagram correlation 1 image

scatter diagram correlation B image


scatter diagram linear regression image

scatter diagram regression image

scatter diagram correlation image


Dr. Robert Sweetland's notes
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