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92 protocols using «proc freq»

1

Frequency Analysis of Adhesion Genes

2025
The frequency of each agr type and MSCRAMM genes was calculated as the proportion of positive isolates for each gene divided by the total number of isolates in the clinical and subclinical categories. Chi-square or Fisher Exact tests (PROC FREQ; SAS Institute, Cary, NC, USA) were used, with a significance level of 0.05.
Adhesion and invasion cell counts were log-transformed for analysis. Subsequently, the ratio of adhesion to invasion was calculated by dividing the log of adhesion counts by the log of invasion counts. The normality of the response variables was assessed using both statistical tests and graphical analysis. Differences in the medians between clinical severity groups were conducted using the Kruskal–Wallis test followed by Dunn’s post-hoc analysis. Statistical significance was considered when p < 0.05. A correlation of adhesion and invasion genes was obtained using the Mann–Whitney test. Statistical analysis and graphical representation were generated using GraphPad Prism version 8.0.1.
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2

Assessing Urban Heat Island Effects on Plant Flowering

2024
We used three different analysis approaches to test if the probability of flowering differed between plants according to their collection position along the transect. The three approaches capture the UHIE in different ways (Amsterdam urban–rural transect) to reveal at which scale adaptation is occurring. First, we used logistic regressions using distance from the start of the transect as a continuous variable to test if the flowering response showed a gradual change along the transect. Logistic regressions were performed using PROC GENMOD (SAS OnDemand for Academics, SAS Institute Inc., Cary, NC, USA) using Wald chi-square tests. Second, we used Fisher’s exact tests (PROC FREQ, SAS OnDemand for Academics) to test if the proportion of plants that flowered in our vernalization experiments differed between the three main transect districts: urban, suburban, and rural. Third, we used Fisher’s exact tests to test if the proportion of plants that flowered in our vernalization experiments differed between the five subhabitats: street, urban roadside verge, park, rural roadside verge, and dairy farm grassland. For the second experiment involving the short vernalization and control treatments, we fitted separate statistical models to data for each of the two treatment levels, because the vernalization treatment not only induces flowering capacity but also causes a delay in plant development, which makes it difficult to compare flowering dates between plants from the different treatments. However, we also analyzed a single model containing both short and no vernalization treatment levels, which is useful for evaluating the interaction effect between vernalization and different levels of urbanization (PROC GENMOD, SAS OnDemand for Academics, Supplementary Material Part 3).
For the heat experiment, we used linear mixed models to test the effects of temperature, collection position, and their interaction, on total plant biomass. In all models, we included replicate block and temperature treatment as categorical fixed factors and third leaf length at the start of the temperature treatment as a continuous fixed cofactor. In all models, we included “collection location of the accession” and its interaction with temperature treatment as fixed factors, where three separate models used different definitions of “collection location” to reveal the scale at which adaptation occurs: (1) distance from the start position of the transect (continuous cofactor); (2) main transect district (urban, suburban or rural; categorical factor); and (3) subhabitat type (street, urban roadside verge, park, rural roadside verge and dairy farm grassland; categorical factor). Linear models were performed using PROC GLM (SAS OnDemand for Academics). After plotting temperature treatment results as a function of distance to the start of the transect, we visualized trends in growth response at different temperatures along the urban–rural transect by fitting the regression line for each temperature treatment as estimated from a linear model as described above, when fitted to data from each temperature treatment separately. All p-values reported in this manuscript correspond to two-sided statistical testing.
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3

Antibiotic Resistance Patterns in Livestock

2024
The data analysis was performed using Microsoft Excel (Microsoft Corporation). The prevalence of CP was tested using a chi-square test (Proc freq; SAS Institute Inc., 2012). The software Origin was utilized to generate a cluster dendrogram of different animal types based on the relative frequency of resistance combination to different antibiotics. The differences in the inhibition zones of Moringa oil and extracts against CP isolates in cattle, sheep, and goats were tested according to Mann–Whitney. Furthermore, the U. Roc curve of MedCalc statistical software was used for assessing the AUC values of different diagnostic antibiotics and Cohen’s Kappa test was used to test the quality of agreement between tests. In addition, GraphPad Prism software 9.0 (GraphPad, USA) was used to generate the figures Statistical significance was determined by accepting p-values less than 0.05.
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4

Determining NEFA Thresholds for Cow Health

2023
Statistical analyses were performed with SAS software (version 9.4). Initial screening for simple associations of NEFA, at various cut‐points, with diseases, culling risk and pregnancy chance were done with contingency tables and chi‐square statistics (PROC FREQ in SAS). Cows that had a BCS of 3 were classified as thin, a BCS of 3.25 or 3.5 as fair, and a BCS of more than 3.75 as fat. Parity was classified into two groups: group 1: parities 2 and 3 and group 2: parities 4 and more. The determinants of risk of periparturient diseases, culling and the chance of pregnancy were modeled using multivariable logistic regression (PROC GENMOD with binary estimating distribution, logit link function, and compound symmetry covariance structure). Each model contained the effects of the parity group, BCS category, season and the occurrence of dystocia, retained placenta, metritis, lameness and lameness score, and mastitis. Appropriate cut‐points for serum NEFA levels associated with increased risk of cow health events were determined first by creating incremental cut‐points of 0.1 mmol/L of NEFA from 0.1 to 1.0 mmol/L. These cut‐points were evaluated using dichotomous variables, designating a 0 value for all samples below each cut‐point and assigning a value of 1 to all values at or above each cut‐point. These serial thresholds were then contrasted with the occurrence of clinical disease using simple 2 × 2 contingency tables. For metabolites that were retained in the final models, animals were classified as being above or below a series of cut‐points, each of which was tested for association with subsequent outcomes. To determine the best cut‐point, the sensitivity and specificity of the cut‐points were calculated manually and then the cut‐point that had the highest sum of sensitivity and specificity was considered the optimal cut‐point.
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5

Evaluating Mastitis Treatments Using Dairy Cow Data

2023
Each season was analysed separately. Daily milk yield and SCS were analysed using a generalised linear mixed model (GLIMMIX procedure of SAS; SAS Institute Inc., Cary, NC, USA), with the treatment, week of the year, and interaction between the treatment and week as fixed effects. The block was considered a random effect. Post hoc comparisons were performed with a Tukey–Kramer test.
The UHS was analysed, classifying the data into two categories: “clean” (scores 1 and 2) and “dirty” (scores 3 and 4) [11 (link)]. For this analysis, a generalised linear mixed model for a binomial distribution variable was used (GLIMMIX procedure of SAS; SAS Institute Inc., Cary, NC, USA). The fixed effects were the treatment, date of observation of the UHS, and interaction between the treatment and the date of observation, and the block was considered as a random effect. The effect of rainfall (>30 mm) on UHS was studied by a chi-square test (PROC FREQ; SAS Institute Inc., Cary, NC) for each treatment, and the odds ratio (OR) and its 95% CI were reported.
To determine the correlation between the UHS and IMI and between the UHS and SCS, the closest measure of IMI and SCS after UHS observation (1 to 20 days; [11 (link)]) was used, and the Spearman test was carried out.
The relative prevalence of IMI was analysed using a generalised linear mixed model for a binomial distribution variable (GLIMMIX procedure of SAS; SAS Institute Inc., Cary, NC, USA), with fixed effects defined as the treatment, month, and interaction between the treatment and month, and the block with the animal nested as a random effect.
For the analysis of the monthly and cumulative incidence of clinical mastitis, contingency tables were made and analysed by Fisher’s exact test for binomial variables. The 95% confidence intervals were estimated by the Wilson Score method.
For all analyses, a value of p ≤ 0.05 was considered significant and a tendency when 0.05 < p ≤ 0.10.
The results of the bacterial cultures are presented as descriptive statistics according to the calving season for both treatments and include samples of cases of clinical mastitis (first and recurrent events; [25 ]).
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Top 5 protocols citing «proc freq»

1

Varenicline vs. Nicotine Patch for Smoking Cessation

The dichotomous primary outcome was analyzed via logistic regression with model effects comparing the varenicline and C-NRT conditions each with the nicotine patch (reference) condition using reference cell (dummy) coding,19 ,20 and by comparing varenicline versus C-NRT. Similar logistic regression models were used to analyze secondary abstinence outcomes. Risk differences (RDs) were calculated using Proc Freq (SAS Institute) via the RISKDIFF option and are reported for abstinence end points. Also, a Cox regression survival analysis was run (via SAS Proc Phreg) to analyze time to relapse up to 6-months post-quit. Abstinence outcome models included the full intent-to-treat sample (N=1086). Similar results were obtained with both CO cut-offs (≤ 5 ppm and ≤ 9 ppm).
A priori covariates for the adjusted models were: cohort, site, gender, race, income, FTND total score, FTND Item 1, self-reported likelihood of quitting, age, baseline CO, home smoking, prior cessation medication use, and menthol cigarette use. Each a priori covariate was tested in separate logistic regression models that included treatment coding (dummy-coded variables: e.g., patch vs. varenicline), the covariate, and the interaction of the covariate with treatment (for moderation analysis). A Chi-Square analysis was used to test the association between nicotine dependence (FTND Item 1 score) and treatment (C-NRT versus patch), with abstinence at 26 weeks.
The two withdrawal outcomes were analyzed via linear regression models both with and without a corresponding baseline withdrawal covariate (mean score one week pre-TQD).
For abstinence outcomes, our analyses were run assuming that missing observations reflected smoking. Sensitivity analyses were applied to test this assumption via multiple imputation as per Hedeker et al.,21 (link) combined with an assumption that missingness was related to smoking at ORs = 2 or 5. These analyses were conducted with the primary outcome (CO cut-off = 5). Obtained results were essentially the same as those where missing was treated as smoking; only the latter are reported.
A priori power analyses (via SAS Proc Power) focused on the primary outcome and comparisons of either varenicline or C-NRT with the patch condition, and assumed a ten percentage point difference based on treatment differences observed in meta-analyses and estimates of clinical significance.3 We hypothesized a 26 week abstinence rate of 24% for the nicotine patch control condition (n ≈ 227) and >34%, for the varenicline and C-NRT (n’s ≈ 387) conditions,3 ,6 (link),8 (link) yielding power (2-tailed test, α=.05) > 80%. Additionally, there was 80% power to show a > 9 percentage point difference between the varenicline and C-NRT treatments, e.g., 34% versus 44% (no directional hypotheses were formulated).
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2

Magnetic Resonance Imaging Criteria for Canine Glioma

Inter-observer agreement for each MRI criterion was assessed by calculating the value for linearly weighted kappa (κ) for each pair of investigators, providing a total of 10 (κ) values for each criterion (PROC FREQ, SAS 9.2, SAS Institute). The overall level of agreement for each criterion was summarized by the median kappa value for the 10 investigator pairs; values of 0.81–1.00 were considered to indicate excellent agreement; 0.61–0.80, good agreement; 0.41–0.60, moderate agreement; 0.21–0.40, fair agreement; 0.01–0.20, poor agreement, and 0.00, chance agreement (Landis and Koch, 1977 (link)), as previously applied to canine brain MRI studies (Wolff et al., 2012 (link)).
Statistical analysis of the relationship between the MRI criteria and the tumor type and grade was performed in two stages, a preliminary univariate analysis and a final multivariate analysis. For the preliminary univariate analysis, contingency tables were developed. Grade II tumors were compared to grade III and IV tumors for consistency with prior studies (Young et al., 2011 (link)), thus dividing the cases into low-grade and high-grade glioma as in studies of human tumors (Rao et al., 2013 ). Separately, astrocytomas were compared to oligodendrogliomas. Each contingency table was analyzed using a Fisher’s exact test (PROC FREQ, SAS 9.2, SAS Institute) and P < 0.01 was considered significant, because of the high number of putative variables examined. Patterns of contrast enhancement were further investigated post hoc by determining associations with no contrast enhancement and with partial or complete ring enhancement.
For multivariate analysis, forward stepwise logistic regression (PROC LOGIST, SAS 9.2, SAS Institute) was used. Again, grade II tumors were compared to grades III and IV and astrocytomas were compared to oligodendrogliomas. A P value to enter of < 0.20 and to remain of < 0.05 was used. Investigators were entered as dummy variables and the final logistic regression model fit was evaluated using the Hosmer-Lemeshow goodness-of-fit test.
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3

Perinatal Bovine Mortality Risk Factors

Data on risk factors likely to impact perinatal mortality were collected from a pre-designed farmer questionnaire (Table 1). A written herd-level questionnaire to determine farm management practices plausibly linked to perinatal bovine mortality was drafted and piloted with two farm managers at Moorepark Research Centre to assess understanding of the questions. The redesigned questionnaire was emailed to each farmer in January 2010 and in January 2012. The questionnaire contained 17 questions grouped into four sections. Three sections dealt with pre-calving factors; breeding (heifer and cow breeds in the herd, breeds of service sires used on heifers and on cows), pre-calving diet and body condition score (forage, concentrate ration and macro and micronutrient supplementation of heifers and of cows pre-calving and body condition score of heifers and of cows pre-calving), endemic infectious diseases (recent clinical history of endemic infectious diseases, number of dogs and presence of foxes on the farm and vaccines used in heifers and in cows) and one dealt with calving management (timing of transfer of pregnant heifers and of cows to the calving facility, type of calving facility, frequency of observations for imminent calving, duration of natural calving allowed before intervention, type of calving aid used, number of personnel managing calvings, methods used to prevent milk fever and techniques used to resuscitate weak newborn calves). The topics were chosen based on management factors known to impact bovine perinatal mortality [1 (link)]. The questionnaire returns were examined prior to data entry and obvious errors indicating misunderstanding of a question were clarified. Data analysis consisted of tests of association between risk group (High and Low) and the per question responses. To facilitate comparison of preferable and non-preferable variable levels, some outcome variable levels were collapsed. Contingency tables were constructed for each year of observation and for the combined results and tested using Chi Square tests or Fisher’s Exact Test. The latter was included to cover those tables where one or more cell frequencies were ≤5. The LOGISTIC procedure was used to generate odds ratios (OR) and their 95% confidence intervals for these tests. The final model fit was evaluated using the Hosmer and Lemeshow goodness-of-fit test. Differences were considered significant if P ≤ 0.05. All data editing and statistical analyses were carried out using appropriate procedures (Proc FREQ and LOGISTIC in SAS (SAS Institute Inc., Cary, NC, USA)).
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4

Evaluating Sow Vulva Scores and Litter Performance

Statistical Analysis Systems University Edition, version 9.4 (Cary, NC) was used for all statistical analysis. Regression analyses (PROC REG, SAS v.9.4, SAS Inst. Inc., Cary, NC) were completed to evaluate the relationships between BW and VW measures and to generate coefficient of determination values. Group means for each fixed effect level were compared using PROC TTEST. A chi-square (χ 2) analysis was performed (PROC FREQ, SAS v.9.4) to estimate the association between vulva score classification and ability to achieve P1 and P2. Additionally, for each vulva scoring method (VSA, VSB, or FS) mixed model methods (PROC MIXED, SAS v.9.4) were used to analyze the litter performance data, with a model where the fixed effects were: vulva score, sow farm, birth week, and the associated interactions. The random error term was the only random effect included in any model used for analyses. Prior to analyzing litter performance data, data points extending beyond 2.5 SDs from the mean for TB, BA, SB, and MM were considered outliers and were removed from analysis. The number of outliers from any of the analyses ranged from 0 to 6 animals.
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5

Identifying Selection Signatures in Genomes

Loci with high or low allelic differentiation in relation to the expected neutrality, from the 28,860 SNPs in final data, were used as an indication of selection (Hoffmann & Willi, 2008) and were tested by two different methodologies of outlier identification.
BayeScan software V 2.1 (Foll & Gaggiotti, 2008) used a Bayesian approach via Markov Chain Monte Carlo (MCMC), assuming a prior Dirichlet distribution of alleles within populations and a hierarchical Bayesian model. The program calculates posterior odds, from the posterior probability of the models, with and without selection on a locus, using the proportion of loci with a strong increase in FST relative to other loci among the MCMC outputs of its simulations (Beaumont & Balding, 2004). The software was set up with 5,000 burn‐in interactions, followed by 10,000 interactions with thinning interval of 10. Convergence was verified using CODA package for R (Plummer, Best, Cowles, & Vines, 2006) with critical values of −1.96 > z > +1.96. A second analysis was performed using the software Samβada (Joost et al., 2007; Stucki et al., 2014) that used logistic regression models to determine the probability of allele presence/absence in a specific environment. The models were considered significant when the G Score and Wald Score were significant at α = 0.01 threshold with a Bonferroni correction. The G Score can be defined as the ratio between maximum log likelihood of model with the presence of the independent variable and the maximum log likelihood of model without independent variable, or as the independent variable affects in the log likelihood model. The Wald Score tests if goodness of fit is affected when the independent variable is removed from the model. Using the FREQ procedure (Proc FREQ) of SAS v9.3 (SAS Institute Inc. 2011), the agreement between the two methods was evaluated through the Kappa index. The Kappa index is a measure of interrater agreement, between two or more methods: When the observed agreement exceeds chance agreement, kappa is positive, with its magnitude reflecting the strength of agreement. Gene annotations within candidate regions were obtained using the data provided by Ensembl (Cunningham et al., 2015) and NCBI (http://www.ncbi.nlm.nih.gov). To explore the linkage disequilibrium (LD) of selection signatures detected with other FST outliers and with nearby genes, we calculated the LD from these markers using Plink software (Purcell, 2014).
To measure the degree of spatial association for marker signaled as FST outliers by both methods, the Global spatial autocorrelation (Moran's I) was calculated. Moran's I describes the autocorrelation between the values of a variable in a certain location with the values of this same variable in a neighboring location (Druck, Carvalho, Câmara, & Monteiro, 2004), with null hypothesis being that there is no spatial clustering.
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