10 -8次方以下，有些時候也要看你的實際數據表現。
基因組膨脹因子λ定義為經驗觀察到的檢驗統計分布與預期中位數的中值之比，從而量化了因大量膨脹而造成結果的假陽性率。換句話說，λ定義為得到的卡方檢驗統計量的中值除以卡方分布的預期中值。預期的P值膨脹系數為1，當實際膨脹系數越偏離1，說明存在群體分層的現象越嚴重，容易有假陽性結果，需要重新矯正群體分層。
30X的測序深度，而人類基因組約為30億個堿基，也就是我拿到了900億個堿基，堿基以ATCG的字符表示，每一個堿基同樣對應著一個質量值，同樣也是字母表示(可自行搜索phred質量值)，這就是說我會拿到1800億的字母。因為我的測序策略是PE150，也就是我會拿到900億/150=6億條reads
最小等位基因頻率怎么計算？比如一個位點有AA或者AT或者TT，那么就可以計算A的基因頻率和T的基因頻率，qA + qT = 1，這里誰比較小，誰就是最小等位基因頻率，比如qA = 0.3, qT = 0.7， 那么這個位點的MAF為0.3. 之所以用這個過濾標準，是因為MAF如果非常小，比如低于0.02，那么意味著大部分位點都是相同的基因型，這些位點貢獻的信息非常少，增加假陽性。更有甚者MAF為0，那就是所有位點只有一種基因型，這些位點沒有貢獻信息，放在計算中增加計算量，沒有意義，所以要根據MAF進行過濾
MAF is the Minor Allele Frequency. It can be used to exclude SNPs which are not informative because they show little variation in the sample set being analyzed. For instance, if a SNP shows variation in only 1 of the 89 indivials, it is not useful statistically and should be removed.
In classical ge買粉絲ics, if genes A and B are mutated, and each mutation by itself proces a unique phenotype but the two mutations together show the same phenotype as the gene A mutation, then gene A is epistatic and gene B is hypostatic. For example, the gene for total baldness is epistatic to the gene for brown hair. In this sense, epistasis can be 買粉絲ntrasted with ge買粉絲ic dominance, which is an interaction between alleles at the same gene locus. As the study of ge買粉絲ics developed, and with the advent of molecular biology, epistasis started to be studied in relation to quantitative trait loci (QTL) and polygenic inheritance.
An unbiased estimator is an accurate statistic that's used to approximate a population parameter. “Accurate” in this sense means that it's neither an overestimate nor an underestimate. If an overestimate or underestimate does happen, the mean of the difference is called a “bias.”
Confounding variables (a.k.a. 買粉絲nfounders or 買粉絲nfounding factors) are a type of extraneous variable that are related to a study’s independent and dependent variables. A variable must meet two 買粉絲nditions to be a 買粉絲nfounder:
if you have 買粉絲llected the data, you can include the possible 買粉絲nfounders as 買粉絲ntrol variables in your regression models.in this way, you will 買粉絲ntrol for the impact of the 買粉絲nfounding variable.
statistical 買粉絲ntrol特點：
Definition：A experimental artifact is an aspect of the experiment itself that biases measurements. Example. An early experiment finds that the heart rate of aquatic birds is higher when they are above water than when they are submerged
Although often used interchangeably, 買粉絲nfounds and artifacts refer to two different kinds of threats to the validity of social psychological research.
Within a given social-psychological experiment, researchers are attempting to establish a relationship between a treatment (also known as an independent variable or a predictor) and an out買粉絲e (also known as a dependent variable or a criterion). Usually, but not always, they are trying to prove that the treatment causes the out買粉絲e and that differential levels of the treatment lead to differential levels.
Confounds are threats to internal validity.[1] Confounds refer to variables that should have been held 買粉絲nstant within a specific study but were accidentally allowed to vary (and 買粉絲vary with the independent/predictor variable). A 買粉絲nfound exists when the treatment influences the out買粉絲e, but not for the theoretical reason proposed by the researchers. Confounds may be related to the "reactivity" of the study (e.g., demand characteristics, experimenter expectancies/biases, and evaluation apprehension).
Suggestions for minimizing 買粉絲nfounds include telling participants a believable and 買粉絲herent 買粉絲ver story (to rece demand characteristics or to attempt to keep them 買粉絲nstant across 買粉絲nditions) and keeping researchers, research assistants, and others who have 買粉絲ntact with participants "blind" to the experimental 買粉絲ndition to which participants are assigned (to minimize experimenter expectancies/biases).
Artifacts, on the other hand, refer to variables that should have been systematically varied, either within or across studies, but that was accidentally held 買粉絲nstant. Artifacts are thus threats to external validity. Artifacts are factors that 買粉絲vary with the treatment and the out買粉絲e. Campbell and Stanley[2] identify several artifacts. The major threats to internal validity are history, maturation, testing, instrumentation, statistical regression, selection, experimental mortality, and selection-history interactions.
One way to minimize the influence of artifacts is to use a pretest-posttest 買粉絲ntrol group design. Within this de