Download presentation

Presentation is loading. Please wait.

Published byMagdalene Hall Modified over 2 years ago

1
Term 3, 2008Bio753 Advanced Methods III1 Weighted Means and RE models

2
Term 3, 2008Bio753 Advanced Methods III2

3
Term 3, 2008Bio753 Advanced Methods III3

4
Term 3, 2008Bio753 Advanced Methods III4

5
Term 3, 2008Bio753 Advanced Methods III5

6
Term 3, 2008Bio753 Advanced Methods III6

7
Term 3, 2008Bio753 Advanced Methods III7

8
Term 3, 2008Bio753 Advanced Methods III8

9
Term 3, 2008Bio753 Advanced Methods III9 INFERENCE SPACE (Sanders) The choice between fixed and random effects depends in part on the reference population (the inference space) –These studies or people – Studies or people like these –.........

10
Term 3, 2008Bio753 Advanced Methods III10 Random Effects should replace “unit of analysis” Models contain Fixed-effects, Random effects (via Variance Components) and other correlation- inducers There are many “units” and so in effect no single set of units Random Effects induce unexplained (co)variance Some of the unexplained may be explicable by including additional covariates MLMs are one way to induce a structure and estimate the REs

11
Term 3, 2008Bio753 Advanced Methods III11 ACCOUNTING FOR (explaining) UNEXPLAINED VARIABILITY Including regressors can explain (account for) some of unexplained variability Doing so is always a trade-off in that you need to use degrees of freedom to do the explaining Going too far--adding too many regressors-- inflates residual variability In MLMs there is variance at various levels that can potentially be taken into account

12
Term 3, 2008Bio753 Advanced Methods III12 TEACHER EXPECTANCY TEACHER EXPECTANCY (data are in “Datasets” ) Data are from a Raudenbush & Bryk meta-analysis of 19 studies (see Cooper and Hedges,1994) Effect size k = distance between treatment and control group means measured in population standard deviation units SE k = the standard error of the effect size Weeks k = estimated weeks of teacher-student contact prior to expectancy induction

13
Term 3, 2008Bio753 Advanced Methods III13 TEACHER EXPECTANCY TEACHER EXPECTANCY (continued) Each study consisted of either telling teachers that a student had great potential or not All students received a pre-test and a post-test Teachers evaluated progress A positive effect size indicates that the teachers rated students who were “likely to improve” as having improved more than the control group A negative slope on “Weeks” indicates that the more a teacher got to know a student before the experiment,the less the influence of the expectancy intervention

14
Term 3, 2008Bio753 Advanced Methods III14

15
Term 3, 2008Bio753 Advanced Methods III15

Similar presentations

OK

Unit 3b: From Fixed to Random Intercepts © Andrew Ho, Harvard Graduate School of EducationUnit 3b – Slide 1

Unit 3b: From Fixed to Random Intercepts © Andrew Ho, Harvard Graduate School of EducationUnit 3b – Slide 1

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on microcontroller based home security system Ppt on intelligent manufacturing Ppt on you can win pdf Ppt on interchange of sentences for kids Ppt on endangered species of wildlife in india Ppt on landing gear system Download ppt on congruence of triangles class 7 Ppt on astronomy and astrophysics courses Ppt on regulated dc power supply Ppt on professional development plan