scholarly journals Use and Misuse of Mixed Model Analysis of Variance in Ecological Studies

Ecology ◽  
1994 ◽  
Vol 75 (3) ◽  
pp. 717-722 ◽  
Author(s):  
Cynthia C. Bennington ◽  
William V. Thayne
Keyword(s):  
Analysis Of Variance ◽  
Mixed Model ◽  
Model Analysis ◽  
Ecological Studies ◽  
Mixed Model Analysis

A mixed model analysis of variance for multi-environment variety trials

2009 ◽  
Vol 50 (4) ◽  
pp. 735-759 ◽  
Author(s):  
T. Caliński ◽  
S. Czajka ◽  
Z. Kaczmarek ◽  
P. Krajewski ◽  
W. Pilarczyk
Keyword(s):  
Analysis Of Variance ◽  
Mixed Model ◽  
Model Analysis ◽  
Mixed Model Analysis ◽  
Variety Trials

scholarly journals Effect of stocking density and effective fiber on the ruminal bacterial communities in lactating Holstein cows

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9079
Author(s):  
Brooke A. Clemmons ◽  
Mackenzie A. Campbell ◽  
Liesel G. Schneider ◽  
Richard J. Grant ◽  
Heather M. Dann ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Analysis Of Variance ◽  
Bacterial Communities ◽  
Mixed Model ◽  
Diversity Index ◽  
Stocking Density ◽  
Model Analysis ◽  
Mixed Model Analysis ◽  
Rumen Microbiome ◽  
Normally Distributed

Overstocking can be a major issue in the dairy cattle industry, leading to negative changes in feeding and resting behavior. Additional stress imposed and alterations in feeding behavior may significantly impact the rumen microbiome. The rumen microbiome is responsible for the successful conversion of feed to usable energy for its host. Thus, understanding the effects of stocking density on the rumen microbiome is imperative for further elucidation of potentially negative consequences of overstocking in dairy cattle. This study implemented a Latin Square design accounting for four pens of cattle and four treatment periods so that all treatment combinations were assigned to every pen during one period of the study. Two treatment factors, including two levels of physically effective neutral detergent fiber, achieved with addition of chopped straw, and stocking density (100% vs. 142%) of freestalls and headlocks, were combined and tested within a factorial treatment design. Within each pen, three or four cannulated cows (n = 15 total) were sampled for rumen content on the final day of each treatment period. Each treatment was randomly assigned to a single pen for a 14-day period. The V1–V3 hypervariable regions of the 16S rRNA gene were targeted for bacterial analyses. Variables with approximately normally-distributed residuals and a Shapiro–Wilk statistic of ≥0.85 were analyzed using a mixed model analysis of variance with the GLIMMIX procedure with fixed effects of feed (straw vs. no straw), stocking density (100% vs. 142%), and the interaction of feed × stocking density, and random effects of pen, period, feed × stocking × pen × period. Pen was included as the experimental unit in a given period and the sampling unit as cow. Variables included Shannon’s Diversity Index, Faith’s phylogenetic diversity index, chao1, observed OTU, and Simpson’s evenness E as well as most individual taxa. Data were analyzed in SAS 9.4 utilizing the GLIMMIX procedure to perform mixed model analysis of variance. If data were not normally distributed, a ranked analysis was performed. No differences were observed in α-diversity metrics by fiber or stocking density (P > 0.05). Beta diversity was assessed using weighted and unweighted Unifrac distances in QIIME 1.9.1 and analyzed using ANOSIM. No differences were observed in weighted (P = 0.6660; R = −0.0121) nor unweighted (P = 0.9190; R = −0.0261) metrics and R values suggested similar bacterial communities among treatments. At the phylum level, Tenericutes differed among treatments with an interaction of stocking density by feed (P = 0.0066). At the genus level, several differences were observed by treatment, including Atopobium (P = 0.0129), unidentified members of order RF39 (P = 0.0139), and unidentified members of family Succinivibrionaceae (P = 0.0480). Although no diversity differences were observed, taxa differences may indicate that specific taxa are affected by the treatments, which may, in turn, affect animal production.

Diagnostics for Mixed – Model Analysis of Variance

Technometrics ◽  
1987 ◽  
Vol 29 (4) ◽  
pp. 413-426 ◽  
Author(s):  
Richard J. Beckman ◽  
Christopher J. Nachtsheim ◽  
R. Dennis Cook
Keyword(s):  
Analysis Of Variance ◽  
Mixed Model ◽  
Model Analysis ◽  
Mixed Model Analysis

scholarly journals Heating Capacity of ReBound Shortwave Diathermy and Moist Hot Packs at Superficial Depths

2013 ◽  
Vol 48 (4) ◽  
pp. 471-476 ◽  
Author(s):  
Amanda R. Hawkes ◽  
David O. Draper ◽  
A. Wayne Johnson ◽  
Mike T. Diede ◽  
Justin H. Rigby
Keyword(s):  
Analysis Of Variance ◽  
Repeated Measures ◽  
Mixed Model ◽  
Model Analysis ◽  
Triceps Surae ◽  
Tissue Temperature ◽  
Mixed Model Analysis ◽  
Temperature Decay ◽  
Triceps Surae Muscle ◽  
Hot Pack

Context: The effectiveness of a new continuous diathermy unit, ReBound, as a heating modality is unknown. Objective: To compare the effects of ReBound diathermy with silicate-gel moist hot packs on tissue temperature in the human triceps surae muscle. Design:  Crossover study. Setting: University research laboratory. Patients or Other Participants: A total of 12 healthy, college-aged volunteers (4 men, 8 women; age = 22.2 ± 2.25 years, calf subcutaneous fat thickness = 7.2 ± 1.9 mm). Intervention(s): On 2 different days, 1 of 2 modalities (ReBound diathermy, silicate-gel moist hot pack) was applied to the triceps surae muscle of each participant for 30 minutes. After 30 minutes, the modality was removed, and temperature decay was recorded for 20 minutes. Main Outcome Measure(s):  Medial triceps surae intramuscular tissue temperature at a depth of 1 cm was measured using an implantable thermocouple inserted horizontally into the muscle. Measurements were taken every 5 minutes during the 30-minute treatment and every minute during the 20-minute temperature decay, for a total of 50 minutes. Treatment was analyzed through a 2 × 7 mixed-model analysis of variance with repeated measures. Temperature decay was analyzed through a 2 × 21 mixed-model analysis of variance with repeated measures. Results: During the 30-minute application, tissue temperatures at a depth of 1 cm increased more with the ReBound diathermy than with the moist hot pack (F6,66 = 7.14, P < .001). ReBound diathermy and moist hot packs increased tissue temperatures 3.69°C ± 1.50°C and 2.82°C ± 0.90°C, respectively, from baseline. Throughout the temperature decay, ReBound diathermy produced a greater rate of heat dissipation than the moist hot pack (F20,222 = 4.42, P < .001). Conclusions: During a 30-minute treatment at a superficial depth, the ReBound diathermy increased tissue temperature to moderate levels, which were greater than the levels reached with moist hot packs.

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