An Extension of the T-Method of Multiple Comparison to Include the Cases with Unequal Sample Sizes

Spjøtvoll, Emil; Stoline, Michael R.

doi:10.2307/2284534

Cited by 112 publications

(42 citation statements)

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“…For daily growth rates we applied an arcsine transformation prior to a one-way ANOVA. In both analyses, when significant differences were found, we applied a Tukey test (Spjotvoll & Stoline, 1973;Zar, 1999) to locate the differences between the various experimental treatments. Prior to analysis, we verified assumptions of homogeneity of variances using a multivariate test (Anderson, 1958).…”

Section: Discussionmentioning

confidence: 99%

Effects of UVB Radiation on the Initial Stages of Growth of Gigartina Skottsbergii, Sarcothalia Crispata and Mazzaella Laminarioides (Gigartinales, Rhodophyta)

et al. 2006

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The effects of UVB radiation on the growth of macroalgal thalli were evaluated using tetrasporophytic fronds of the Rhodophytes Gigartina skottsbergii, Sarcothalia crispata and Mazzaella laminarioides. The tetrasporophytic fronds were collected from nature and the tetrasporophyte sporelings grown in a temperature regulated chamber at 8 ± 2 • C with a 12L:12D (Light: Dark) photoperiod, Photosynthetically Active Radiation (PAR) of 55 μmol photons m −2 s −1 and seawater enriched with 20 mL L −1 of Provasoli medium. We exposed the thalli of these macroalgae to PAR (55 μmol photons m −2 s −1 ) and three treatments using a combination of PAR with three different levels of UVB radiation (0.10, 0.15 and 0.23 W m −2 for G. skottsbergii and S. crispata and 0.02, 0.05 and 0.10 W m −2 for M. laminarioides) during a period of 71 days. Growth of thalli was quantified by measuring their length using digitized photographs of samples.Important differences were detected in the growth of individuals cultured under the effects of UVB radiation, when compared to the control (i.e. plants exposed to PAR only). In the case of G. skottsbergii and S. crispata higher levels of UVB radiation resulted in slower growth of thalli. In nearly all measurements for the first two species, UVB radiation levels of 0.1 W m −2 induced differences in thallus growth, while for M. laminarioides levels of UVB radiation of 0.1 W m −2 were effective only after a prolonged period of exposure.Differential effects of UVB radiation on G. skottsbergii, S. crispata and M. laminarioides could interfere with the natural populations of these economically important macroalgal species in southern Chile, where they occur under the annual influence of the Antarctic Ozone Hole and the general thinning of the ozone layer.

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Section: Discussionmentioning

confidence: 99%

Effects of UVB Radiation on the Initial Stages of Growth of Gigartina Skottsbergii, Sarcothalia Crispata and Mazzaella Laminarioides (Gigartinales, Rhodophyta)

et al. 2006

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“…Spjotvoll and Stoline (1973) multiple comparisons for groups with unequal n's were used for post hoc analysis. For the analysis of self-administration under the PR schedule, the number of infusions obtained, rather than the final ratio completed, was used as a dependent variable because the final ratios were derived from an escalating exponen-418 tial function and thus violated ANOVAs assumption of the homogeneity of variance.…”

Section: Data Analysesmentioning

confidence: 99%

“…The number of reinforcers, on the other hand, was a natural logarithmic function of the ratio value and was therefore amenable to parametric analysis (Roberts and Richardson 1992). Thus, similar to behavioral sensitization, self-administration data were subjected to a two-way ANOVA analysis (Pretreatment Condition×Test Day) and to Spjotvoll and Stoline (1973) post hoc multiple comparisons. Figure 1 illustrates the effects of the d-amphetamine challenge on the stereotyped behaviors in both salineand d-amphetamine-pretreated animals.…”

Section: Data Analysesmentioning

confidence: 99%

Pre-exposure of rats to amphetamine sensitizes self-administration of this drug under a progressive ratio schedule

1998

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Two groups of male rats were tested to determine whether pre-exposure to d-amphetamine would enhance the motivation to self-administer the drug under a progressive ratio schedule of reinforcement. In the first phase of the experiment, one group of rats received d-amphetamine (2 mg/kg IP), while a second group received saline on alternate days for a total of ten injections. Following a 21-day drug withdrawal period, behavioral sensitization was confirmed by a significant increase in amphetamine-induced stereotypy in the d-amphetamine-pretreated group, relative to the saline-pretreated group. In the second phase of the study, all rats were implanted with chronic jugular catheters and trained to self-administer d-amphetamine (0.2 mg/kg per infusion) under a fixed-ratio schedule of reinforcement. The progressive ratio paradigm was then imposed for 7 consecutive days; d-amphetamine-pretreated rats attained significantly higher break points than saline-pretreated animals. These data suggest that pre-exposure to d-amphetamine may enhance the motivation to self-administer this drug.

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“…For posthoc comparisons between individual years, a Tukey HSD corrected for unequal sample sizes according to Spjotvoll and Stoline (1973) was used. Ten adult males and gynes each and and 20 white to slightly colored male and female pupae from samples preserved in 70 % ethanol were dried for 6 h at 60°C and weighed in groups of 10.…”

Section: Methodsmentioning

confidence: 99%

Stenamma debile (Hymenoptera, Formicidae): Productivity and sex allocation across three years

Buschinger

Heınze

2001

Insectes soc.

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The numerical sex ratios of the facultatively polygynous ant Stenamma debile summed over several collecting sites in southern Germany were 255 males/gyne in 1997, 1.69 males/gyne in 1998 and 5.59 males/gyne in 1999. A large number of female sexuals were produced in queenless colonies, suggesting an inhibitive effect of queens on the production of gynes. Production of males and new workers varied little between the three study years. Production of sexuals plus workers covaried with queen number and worker number. Sex ratio was negatively associated with queen number and positively correlated with total sexual production. Between-year variation of sex ratios is probably correlated with differences in environmental conditions. Several mated young queens were found in colonies after the mating seasons in every year. Recruitment of queens was very low in the summer of 1997, and only two of 115 queens from 28 colonies appeared to be young, recently adopted queens. In contrast, 17 young and 59 older queens were collected from 26 colonies in fall 1999. Queen number thus increased by 28.8% in 1999, but over all three years of 325 queens only 11.4 % were young queens. Incipient colonies with single queens were never observed. Colony structure and productivity of S. debile, as in other ants, apparently vary considerably over periods of several years. Census data from one particular year, and even from three consecutive years, were not sufficient to clarify the causes of variation in sex allocation.

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An Extension of the T-Method of Multiple Comparison to Include the Cases with Unequal Sample Sizes

Cited by 112 publications

References 0 publications

Effects of UVB Radiation on the Initial Stages of Growth of Gigartina Skottsbergii, Sarcothalia Crispata and Mazzaella Laminarioides (Gigartinales, Rhodophyta)

Effects of UVB Radiation on the Initial Stages of Growth of Gigartina Skottsbergii, Sarcothalia Crispata and Mazzaella Laminarioides (Gigartinales, Rhodophyta)

Pre-exposure of rats to amphetamine sensitizes self-administration of this drug under a progressive ratio schedule

Stenamma debile (Hymenoptera, Formicidae): Productivity and sex allocation across three years

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