PARAMETRIC TEST
t-TEST (SAMPLE, POOLED OR UNPAIRED AND PAIRED)
ANOVA (ONE WAY ANOVA AND TWO WAY ANOVA)
T-TEST
• The t-test assesses whether the means of two groups are statistically different from each other.
Merits:
• It reduces the possibility of guessing the correct answer.
• It covers greater amount of contents than matching types test.
Demerits
• It is only appropriate for questions that can be answered by short responses.
• There is a difficult in scoring when the questions are not prepared properly and clearly.
1.717
F tabulated value 3.11
1.703
ANALYSIS OF
VARIANCE (ANOVA)
ANOVA (ONE WAY ANOVA AND TWO WAY ANOVA)
WHY ANOVA?
• Professor R.A. Fisher was the first man to use the term ‘Variance’* and, in fact, it was he who
developed a very elaborate theory concerning ANOVA, explaining its usefulness in practical
field.
• The ANOVA technique is important in the context of all those situations where we want to
compare more than two populations such as in comparing the yield of crop from several varieties
of seeds, the gasoline mileage of four automobiles, the smoking habits of five groups of
university students and so on.
• In such circumstances one generally does not want to consider all possible combinations of two
populations at a time for that would require a great number of tests before we would be able to
arrive at a decision. This would also consume lot of time and money, and even then certain
relationships may be left unidentified (particularly the interaction effects).
• Therefore, one quite often utilizes the ANOVA technique and through it investigates the
differences among the means of all the populations simultaneously.
One Way ANOVA
EXAMPLE
• Set up an analysis of variance table for the following per acre
production data for three varieties of wheat, each grown on 4 plots
and state if the variety differences are significant.
TWO Way ANOVA
Example
We find that differences concerning varieties of seeds are insignificant at 5% level as
the calculated F-ratio of 4 is less than the table value of 5.14, but the variety
differences concerning fertilizers are significant as the calculated F-ratio of 6 is more
than its table value of 4.76.
F(2,12) 3.89