You can change the data type of a column in the codebook, but this wonвЂ™t affect the data itself unless you set the return argument to вЂњdataвЂќ. MEC exam weights are appropriate for this subsample.Pet_data $ followup id set to dataType string #> pet set to dataType string #> happy set to dataType float cb #> Codebook for pets (Psych-DS 0.1.0) #> #> Dataset Parameters #> #> * name: pets #> * schemaVersion: Psych-DS 0.1.0 #> #> Column Parameters #> #> * id (string): Pet ID #> * pet (string): Pet Type #> * Levels #> * cat: Cat Owners #> * dog: Dog Owners #> * ferret: Ferret Owners #> * Ordered: FALSE #> * happy (float): Happiness Score #> * followup (bool): Followed up 2 weeks later #> * Levels #> * 0: No #> * 1: Yes #> * Ordered: FALSE For Mean T/S Ratio refers to the standard deviation corresponding to the mean of the 3 T/S ratio values obtained for each sample. While comparisons across studies of telomere length in base pairs are commonly done, it is not highly accurate. In this case, results from NHANES are comparable to other studies performed in the Blackburn Lab and may be similar to other PCR-derived measures of telomere length if they used the same methods as written here. Base pair estimates are only comparable for T/S ratio data produced with the same reference standard and the same lab procedures.

While they tend to be highly correlated, they often have different means. It is important to note that there is wide variance in telomere length measures across labs and types of assays. The conversion from T/S ratio to bp is calculated based on comparison of telomeric restriction fragment (TRF) length from Southern blot analysis and T/S ratios using DNA samples from the human diploid fibroblast cell line IMR90 at different population doublings. TeloMean: Mean T/S ratio which is measured telomere length relative to standard reference DNA.ДЇor researchers who wish to convert T/S ratio to base pairs (bp), the formula is (3,274 + 2,413 * (T/S)). The interassay coefficient of variation was 6.5%. The mean and standard deviation of the T/S ratio were then calculated normally. For each sample, any potential outliers were identified and excluded from the calculations (< 2% of samples). Runs with more than 4 control DNA values falling outside 2.5 standard deviations from the mean for all assay runs were excluded from further analysis (< 6% of runs).

Control DNA values were used to normalize between-run variability. Assay runs with 8 or more invalid control wells were excluded from further analysis (< 1% of runs). Each assay plate contained 96 control wells with 8 control DNA samples. Sample plates were assayed in groups of 3 plates, and no 2 plates were grouped together more than once.

The samples were assayed on duplicate wells, resulting in 6 data points. Each sample was assayed 3 times on 3 different days. Elizabeth Blackburn at the University of California, San Francisco, using the quantitative polymerase chain reaction (PCR) method to measure telomere length relative to standard reference DNA (T/S ratio), as described in detail elsewhere (Needham et al, 2013 Cawthon, 2002). The telomere length assay was performed in the laboratory of Dr. Telomeres are a protective nucleoprotein structure at each chromosome end. This information leads to advances in the prevention and treatment of disease. DNA provides important information on genetic or hereditary patterns of disease or risk of disease. A small portion of the blood samples is stored to conduct later analyses on DNA samples. Most of the findings from the analyses of the blood samples are available immediately such as the data on cholesterol and triglyceride levels in the population. Blood samples are obtained from participants in the NHANES surveys.

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