Comparing treatment means correctly and appropriately

1985 ◽  
Vol 15 (6) ◽  
pp. 1142-1148 ◽  
Author(s):  
Carl W. Mize ◽  
Richard C. Schultz
Keyword(s):  
Analysis Of Variance ◽  
Multiple Comparison ◽  
Response Models ◽  
Major Treatment ◽  
The Mean ◽  
The Difference ◽  
Set Up ◽  
Multiple Comparison Procedures ◽  
Range Test ◽  
Selection Of

Many researchers set up an experiment, make measurements, do an analysis of variance, calculate the mean response for each treatment, and then try to decide if the treatment means are significantly different and why. Duncan's multiple-range test is frequently used to test the difference among treatment means. It is, however, only one of a number of techniques that can be used to examine treatment means. Some researchers are unaware of the different techniques and that the interpretation of the results of an experiment can be strongly influenced by the technique used. In fact, using an inappropriate technique can lead to making incorrect recommendations and to completely missing major treatment effects. Selection of the appropriate technique to use for a particular experiment depends upon the nature of the treatments and the objectives of the research. This paper discusses four techniques (ranking treatment means, multiple comparison procedures, fitting response models, and using contrasts to make planned comparisons) that can be used to examine treatment means and presents examples of each one.

scholarly journals The partial circulant diallel cross at the interpopulation level

1999 ◽  
Vol 22 (2) ◽  
pp. 249-255 ◽  
Author(s):  
José B. Miranda Filho ◽  
Roland Vencovsky
Keyword(s):  
Analysis Of Variance ◽  
Combining Ability ◽  
Diallel Cross ◽  
General Combining Ability ◽  
Coefficient Of Determination ◽  
Alternative Analysis ◽  
The Mean ◽  
The Difference ◽  
Selection Of ◽  
Partial Diallel

The partial circulant diallel cross mating scheme of Kempthorne and Curnow (Biometrics 17: 229-250, 1961) was adapted for the evaluation of genotypes in crosses at the interpopulation level. Considering a random sample of n lines from base population I, and that each line is crossed with s lines from opposite population II, there will be ns sampled crosses that are evaluated experimentally. The means of the ns sampled crosses and the remaining n(n - s) crosses can be predicted by the reduced model <img src="http:/img/fbpe/gmb/v22n2/0291e1.gif" align="absmiddle"> where Yij is the mean of the cross between line i (i = 1,2,...,n) of population I and line j (j = 1',2',...,n') of population II; µ is the general mean, and gi and gj refer to general combining ability effects of lines from populations I and II, respectively. Specific combining ability (Sij) is estimated by the difference <img src="http:/img/fbpe/gmb/v22n2/0291e2.gif" align="absmiddle">. The sequence of crosses for each line (i) is [i x j], [i x (j + 1)], [i x (j + 2)], ..., [i x (j + s -1)], starting with i = j = 1 for convenience. Any j + s -1 > n is reduced by subtracting n. A prediction procedure is suggested by changing gi and gj by the contrasts <img src="http:/img/fbpe/gmb/v22n2/s_ti.gif" alt="s_ti.gif (188 bytes)"> i = <img src="http:/img/fbpe/gmb/v22n2/s_ytra.gif" alt="s_ytra.gif (986 bytes)"> i. - <img src="http:/img/fbpe/gmb/v22n2/s_ytra.gif" align="absmiddle"> .. and <img src="http:/img/fbpe/gmb/v22n2/s_ti.gif" align="absmiddle">j = <img src="http:/img/fbpe/gmb/v22n2/s_ytra.gif" align="absmiddle">.j - <img src="http:/img/fbpe/gmb/v22n2/s_ytra.gif" align="absmiddle">..; the correlation coefficient (r) was used to compare the efficiency of <img src="http:/img/fbpe/gmb/v22n2/s_gtil.gif" align="absmiddle">'s and <img src="http:/img/fbpe/gmb/v22n2/s_tiac.gif" align="absmiddle">'s for selection of lines and crosses. The analysis of variance is performed with the complete model Yij = µ + gi + gj + sij + <img src="http:/img/fbpe/gmb/v22n2/s_e_.gif" align="absmiddle">ij, and the sum of squares due to general combining ability is considered for each population separately. An alternative analysis of variance is proposed for estimation of the variance components at the interpopulation level. An analysis of ear length of maize in a partial diallel cross with n = 10 and s = 3 was used for illustration. For the 30 interpopulation crosses analyzed the coefficient of determination (R2), involving observed and estimated hybrid means, was high for the reduced (g) model [R2 (<img src="http:/img/fbpe/gmb/v22n2/s_yac.gif" align="absmiddle">ij, Yij) = 0.960] and smaller for the simplified (<img src="http:/img/fbpe/gmb/v22n2/s_ti.gif" align="absmiddle">) model [R2 (<img src="http:/img/fbpe/gmb/v22n2/s_yac.gif" align="absmiddle">ij, Yij) = 0.889]. Results indicated that the proposed procedure may furnish reliable estimates of means of hybrids not available in the partial diallel.

scholarly journals Do experienced physiotherapists apply equal magnitude of force during a grade I central pa on the cervical spine?

2004 ◽  
Vol 60 (4) ◽  
Author(s):  
M. Conradie ◽  
E. Smit ◽  
M. Louw ◽  
M. Prinsloo ◽  
L. Loubser ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Spinal Disorders ◽  
Joint Mobilization ◽  
Treatment Techniques ◽  
Average Maximum ◽  
Manual Examination ◽  
The Mean ◽  
The Difference ◽  
Posterior Anterior ◽  
Selection Of

Background and purpose: Physiotherapists frequently use central posterior-anterior (PA) joint mobilization techniques for assessing and managing spinal disorders. Manual examination findings provide the basis for the selection of treatment techniques. From the literature it is evident that the level of reliability varies when physiotherapists perform different mobilization techniques. Repeatability of mobilization techniques is important for better physiotherapy management. The aim of the study was to determine whether experienced physiotherapists apply equal magnitude of force during a grade I central PA mobilisation technique on the cervical spine. Another aim was to determine the variation in the magnitude of forceapplied by each individual physiotherapist. Subjects: Sample of convenience, consisting of sixteen (n=16) selected qualified physiotherapists with experience inOrthopaedic Manual Therapy.Methods: A grade I central PA was performed on the Flexiforce TM sensors positioned on C6 of the same asymptomatic model to measure the applied magnitude of force. Two separate measurements, each lasting 30-seconds, were obtained.Results: The average maximum peak force applied by the majority of physiotherapists (87.5%) was between 10.95gand 72g. The difference in the forces applied for the two measurements ranged between 0.64g and 24.4g. The BlandAltman scatterplot determined the mean of the difference between measurement one and two, calculated for the group, was zero. When comparing the two measurements, little variation was noted in the forces applied, as well as the coefficient of variation for each physiotherapist.Conclusion and Discussion: Current results demonstrated good intra-therapist and moderate to good inter-therapist repeatability. Further research is required to generalize results.

Seed size influences the coleoptile length of wheat

1988 ◽  
Vol 28 (4) ◽  
pp. 521 ◽  
Author(s):  
PS Cornish ◽  
S Hindmarsh
Keyword(s):  
Triticum Aestivum ◽  
Seed Size ◽  
Seed Weight ◽  
Size Class ◽  
Adult Plant ◽  
Coleoptile Length ◽  
Seed Width ◽  
The Mean ◽  
The Difference ◽  
Selection Of

Variation in coleoptile length within and between 2 cultivars of semidwarf wheat (Triticum aestivum) was related to seed size. Seeds of cvv. Banks and Kite were separated by sieving for width into the size classes of >2.75, 2.75-250, 2.50-2.25 and 2.25- 2.00 mm. The mean grain weights of ungraded samples were 43.1 mg (Kite) and 34.3 mg (Banks), and for the subsamples were 52.4, 37.9, 30.4 and 20.7 mg (Kite) and 41.4, 33.2, 25.8 and 19.1 mg (Banks). The effect of size class on coleoptile length was significant (P<0.01). Over both cultivars, coleoptile length declined by 0.37 mm per mg reduction in seed weight. Kite produced the longer coleoptiles overall, 87.5 mm compared with 59.0 mm for Banks. However, only 3.3 mm of this difference can be accounted for by the mean difference in seed weight (8.8 mg) and the effect of seed weight on coleoptile length (0.37 mm/mg). Genetic differences, apart from adult plant height, appear to explain most of the difference in coleoptile length between the cultivars. There was considerable genetic variability within genotypes. In Banks, with seed width >2.75 mm (41.4 mg per seed), the lengths of coleoptiles ranged from 24-89 mm (mean 65.1 mm), suggesting considerable scope for the selection of genotypes with longer coleoptiles.

Simultaneous Multiple Comparison Procedures for Categorical Data

1986 ◽  
Vol 20 (3) ◽  
pp. 350-359 ◽  
Author(s):  
Wayne Hall ◽  
Kevin D. Bird
Keyword(s):  
Analysis Of Variance ◽  
Categorical Data ◽  
Multiple Comparisons ◽  
Multiple Comparison ◽  
Multiple Comparison Procedures

Methods are outlined for performing simultaneous multiple comparisons between groups when the dependent variable is one in which subjects are assigned to one of two or more categories. These methods provide tests which are analogous to Scheffe- and Bonferroni-adjusted tests of contrasts in the analysis of variance. Examples are provided of each of these procedures.

scholarly journals Psychological Stresses and Abuse of Kindergarten Children among Working and Non- Working Mothers

2012 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Aisheh. H. Tawalbeh ◽  
Hasan Al- Zawaydeh
Keyword(s):  
Child Abuse ◽  
Analysis Of Variance ◽  
Working Mothers ◽  
Statistical Difference ◽  
Kindergarten Children ◽  
Face Validity ◽  
Future Studies ◽  
The Mean ◽  
The Difference ◽  
Mean Differences

The study goal was to investigate the stress among working and non-working mothers and the abuse of their kindergarten age children. Two instruments were developed to measure the stress with two versions for working and non-working mothers, and a child abuse tool. Face validity and retest reliability were conducted. The stress tool contained 25 Items. The tools were administered to a sample of 400, working (200) and nonworking (200) mothers in Amman. A t-test for independent samples was used to test the difference between means of stress and child abuse for working and non-working mothers. Also, two-way analysis of variance was conducted to find the mean differences of the three abuse dimensions: physical, psychological and neglects for working and non-working mothers. Results showed statistical difference (p < 0.05) between means of stress in favor of working mothers, but the difference between means of abuse was in favor of nonworking mothers. The results also showed statistical significant differences (p < 0.05) in the three domains of physical, psychological and neglect abuse, in favor of the non-working mothers. Implications and recommendations for future studies were suggested. 

scholarly journals Resprouting Responses Dynamics of Schima superba Following a Severe Ice Storm in Early 2008 in Southern China: A Six-Year Study

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 184
Author(s):  
Yonghui Cao ◽  
Benzhi Zhou ◽  
Xiaoming Wang ◽  
Lianhong Gu
Keyword(s):  
Secondary Forest ◽  
Southern China ◽  
Size Class ◽  
Ice Storm ◽  
Basal Diameter ◽  
Schima Superba ◽  
The Mean ◽  
The Difference ◽  
Set Up ◽  
Damage Types

In 2008, an unexpected and severe ice storm affected the forest of southern China. This storm caused damage in regeneration of an important dominant tree, Schima superba (Gugertree). To study this damage, we set up permanent monitoring plots in an ice-storm-damaged subtropical evergreen broad-leaved secondary forest dominated by S.superba in Jianglang Mountains, China. We surveyed the damage to all trees with a minimum basal diameter of 4 cm and monitored their growth for 6 consecutive years. We analyzed the degrees and types of damage for S.superba and their relationships with resprouting characteristics. The results revealed that the main damage types of S.superba were decapitation (45.45%) and uprooting (28.41%). The distribution percentage for both decapitated and uprooted trees were commonly highest in the range of 10–16 cm basal diameter (BD) size class. A great number of individuals sprouted vigorously after the storm. The mean total sprout number and sprout biomass per tree for S.superba varied by tree BD size class. During the first three years after the ice storm, decapitated trees of larger BD classes produced more sprouts per tree than trees of smaller BD classes. However, the opposite trend was seen in uprooted and leaning trees. There was a trade-off between the total number and length of the sprouts. The difference of mean sprouts number and biomass per tree with size class was mainly related to the damage types. As the recovery progressed since the ice storm, the number of sprouts and sprout biomass in uprooted trees was found mainly on the middle trunk sections of uprooted trees, but in the upper sections of decapitated trees. After six years, the mean number of sprouts per tree, on different parts of the tree and for the three types of damaged trees all declined; however, sprout biomass per tree all increased. The mean number of sprout and sprout biomass per tree on different sections for decapitated trees was always highest over time since the storm. Our study will help to provide data on resprouting ability to develop a predictive model for resprouting.

Anthropogenic stress and natural selection: variability in radish biomass accumulation increases with increasing SO2 dose

1990 ◽  
Vol 68 (1) ◽  
pp. 102-106 ◽  
Author(s):  
James S. Coleman ◽  
Harold A. Mooney ◽  
William E. Winner
Keyword(s):  
Natural Selection ◽  
Biomass Accumulation ◽  
Strong Relationship ◽  
Genotypic Differences ◽  
Anthropogenic Stress ◽  
Plant Populations ◽  
Response Models ◽  
The Mean ◽  
Selection Of ◽  
Statistical Functions

Although there is a strong relationship between genetically based variability of a given character and the potential for natural selection to act on that character, most studies of the effects of environmental factors on plants examine the mean responses of plants in a population and not the variability among plants in the population. Yet variability in the response among individuals to an environmental stress could foretell changes in a population that might not be evident from examination of mean responses. Here we report an analysis of data from several experiments on radish plants showing a significant relationship between the coefficient of variation for biomass production by radish plants and the concentration of SO2 at which these plants were fumigated. Increased variability as a result of SO2 exposure may have been due to genotypic differences in SO2 resistance among plants, suggesting a route by which the rapid selection of SO2 resistant plant populations may occur in habitats characterized by severe SO2 stress. Increased variability may have also been due to the effect of SO2 on processes controlling phenotypic plasticity of radish growth. Since SO2 affected variability without necessarily affecting mean plant growth, these results also show that examination of variability in the responses of plants to stresses may be equally or more biologically meaningful than sole examination of mean responses. Furthermore, these results show that care must be taken when constructing parametrically derived dose–response models for predicting the effect of SO2 on plants. If it is common for SO2 to increase the amount of variation in plant populations, then parametric statistical functions would be an inappropriate tool for predicting the effect of SO2 on plants.

Contingent and Noncontingent Schedules of Continuous and Partial Reward in Rats

1972 ◽  
Vol 30 (3) ◽  
pp. 975-982
Author(s):  
Patrick E. Campbell ◽  
Dean L. Fixsen
Keyword(s):  
Analysis Of Variance ◽  
Partial Reward ◽  
Albino Rats ◽  
Extinction Performance ◽  
Contingent Reward ◽  
The Mean ◽  
The Difference ◽  
Dissonance Theory

The effects of contingent reward (R) and nonreward (N) and noncontingent reward (r) and nonreward (n) on extinction performance were investigated. Both R and N were delivered contingently on a runway running response while r and n were delivered by placing Ss directly into the goal box. In acquisition, the 32 albino rats were given 5 contingent trials and 4 noncontingent placements each day for 2 days. Group CC received the daily sequence RrRrRrRrR; Group CP, RnRrRnRrR; Group PC, RxNrRrNrR; and Group PP, RnNrRnNrR. 15 extinction trials were given with 5 trials per day. An analysis of variance applied to the mean log total times in extinction showed that Group CP was significantly more resistant to extinction than Group CC and that Group PP was more resistant to extinction than Group PC. Neither the difference between Groups CC and PC nor the difference between Group CP and PP approached significance. The results were discussed in terms of their relevance to the modified aftereffects hypothesis and dissonance theory.

scholarly journals Correlation between Personality Types and Color Shade Preference

2014 ◽  
Vol 1 (4) ◽  
Author(s):  
Divya Ghorawat ◽  
Ravina Madan
Keyword(s):  
Standard Deviation ◽  
Preference Test ◽  
Personality Types ◽  
Personality Test ◽  
Age Group ◽  
Colour Preference ◽  
Individual Personality ◽  
The Mean ◽  
The Difference ◽  
Selection Of

The main aim of this study was to find out whether the color shade preferences of individuals, grouped according to their personality types are alike or not. The researchers also tried to study the difference in color shade preferences based on gender differences. The objective was to understand whether the color shade preferences of individuals are affected by their individual personality types or not and whether gender plays any role in selection of color shades of individuals. The study sample consisted of a total of 80 subjects, randomly selected from within the age group of 18-25. An attempt was made to maintain a balance between two genders and across the ages. The research instruments used were Eysenck’s Personality Test (to measure the personality types) and a separate Colour Bar- Colour Preference Test was designed to serve the purpose of this study. The subjects were made to fill both the questionnaires and then the items were scored and results were analyzed. Positive scoring was done for Eysenck’s personality questionnaire and negative scoring was used to score the Colour Bar-Colour Preference Test. The data collected was divided into: Introverts (female, male) and Extroverts (female, male). From the data collected the mean, standard deviation and correlation between extraversion scores and the most preferred colour scores, for all the four groups. The mean, standard deviation, and correlation for the four groups was found to be 436.4 (IF), 529.2 (IM), 504 (EF), 453.4 (EM); 5.47 (IF), 6.52 (IM), 5.48 (EF), 6.93(EM); -0.3 (IF), -0.1 (IM), 0.1 (EF) and 0.5 (EM) respectively. From this the conclusion was drawn that there was no significant correlation found between the personality types and colour shade preferences of the subjects except in the case of extroverted males. Recommendations: Increase the sample size as that proved to be a limitation to this study. A study across ages is also possible and might give different results.

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