An alysis o f va riance anova
This presentation is the property of its rightful owner.
Sponsored Links
1 / 12

An alysis o f Va riance (ANOVA) PowerPoint PPT Presentation


  • 63 Views
  • Uploaded on
  • Presentation posted in: General

An alysis o f Va riance (ANOVA). ANOVA. More than two samples Can test multiple factors at the same time Multiple-way ANOVA One factor: One-way ANOVA E.g. Are there any difference of the heights of students from class A, B, C and D? Two factors: Two-way ANOVA

Download Presentation

An alysis o f Va riance (ANOVA)

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


An alysis o f va riance anova

Analysis of Variance(ANOVA)


Anova

ANOVA

  • More than two samples

  • Can test multiple factors at the same time

    • Multiple-way ANOVA

  • One factor: One-way ANOVA

    • E.g. Are there any difference of the heights of students from class A, B, C and D?

  • Two factors: Two-way ANOVA

    • E.g. Are there any difference of the heights of students from class A, B, C and D and also between the sexes?


Assumptions for anova

Assumptions for ANOVA

  • Normal distribution

  • Homogeneity of variances

Most important!

Otherwise, you have to use non-parametric Kruskal-Wallis test


An example lab 5 e g 6

An example (Lab 5, e.g. 6)

  • Four dietary treatments applied to the snails

  • Measurement: shell length


An alysis o f va riance anova

1. Plot a bar chart


An alysis o f va riance anova

2. Test for homogeneity of variances

Ho: equal variances

Ha: unequal variances

Fmax test

1

Fmax= Varmax / Varmin

= 4.6 / 3.5

= 1.3143

Calculated Fmax < Critical F0.05(2),5,5 = 7.15

Accept Ho

Equal variances (p>0.05)


An alysis o f va riance anova

2. Test for homogeneity of variances

Ho: equal variances

Ha: unequal variances

Fmax test

2

Calculated F = 1.3143

Critical F0.05(2),5,5 = 7.15

Accept Ho

Equal variances (p>0.05)


An alysis o f va riance anova

i-1

n-1

3. One-way ANOVA

Ho: equal mean among the diets

Ha: unequal mean among the diets

Cal F > Crit F, p<0.05

Reject Ho, unequal means


An alysis o f va riance anova

In SPSS,

1. Plot a bar chart


An alysis o f va riance anova

2. One-way ANOVA

2

1

3

Only SPSS allows post-hoc Tukey test

4


An alysis o f va riance anova

*


An alysis o f va riance anova

a

b

a

a


  • Login