U Glossary in C#.NET

Scanner PDF417 in C#.NET U Glossary

Mode most common value in a distribution Mound-shaped (bell-shaped) distribution in which Parameter measure that describes a population Percentile rank proportion of terms in the distri-

data values tend to cluster about the center of the distribution; characteristic of a normal distribution Mutually exclusive events events that cannot occur simultaneously; if one occurs, the other doesn t Negatively associated larger values of one variable are associated with smaller values of the other; see associated Nonresponse bias occurs when subjects selected for a sample do not respond Normal curve familiar bell-shaped density curve; symmetric about its mean; defined in terms of its mean and standard deviation; f (x ) = 1

1 x 2

2

Normal distribution distribution of a random vari-

able X so that P (a < X < b) is the area under the normal curve between a and b Null hypothesis hypothesis being tested usually a statement that there is no effect or difference between treatments; what a researcher wants to disprove to support his/her alternative Numerical data see quantitative data Observational study when variables of interest are observed and measured but no treatment is imposed in an attempt to influence the response Observed values counts of outcomes in an experiment or study; compared with expected values in a chi-square analysis One-sided alternative alternative hypothesis that varies from the null in only one direction One-sided test used when an alternative hypothesis states that the true value is less than or greater than the hypothesized value Outcome simple events in a probability experiment Outlier a data value that is far removed from the general pattern of the data P(A and B) probability that both A and B occur; P(A and B ) = P (A) P ( A |B ) P(A or B) probability that either A or B occurs; P(A or B ) = P(A) + P(B) P (A and B ) P value probability of getting a sample value at least as extreme as obtained by chance alone assuming the null hypothesis is true

butions less than the value being considered Placebo an inactive procedure or treatment Placebo effect effect, often positive, attributable to the patient s expectation that the treatment will have an effect Point estimate value based on sample data that represents a likely value for a population parameter Positively associated larger values of one variable are associated with larger values of the other; see associated Power of the test probability of rejecting a null hypothesis against a specific alternative Probability distribution identification of the outcomes of a random variable together with the probabilities associated with those outcomes Probability histogram histogram for a probability distribution; horizontal axis are the outcomes, vertical axis are the probabilities of those outcomes Probability of an event relative frequency of the number of ways an event can succeed to the total number of ways it can succeed or fail Probability sample sampling technique that uses a random mechanism to select the members of the sample Proportion ratio of the count of a particular outcome to the total number of outcomes Qualitative data data whose values range over categories rather than values Quantitative data data whose values are numerical Quartiles 25th, 50th, and 75th percentiles of a dataset Random phenomenon unclear how any one trial will turn out, but there is a regular distribution of outcomes in a large number of trials Random sample sample in which each member of the sample is chosen by chance and each member of the population has an equal chance to be in the sample Random variable numerical outcome of a random phenomenon (random experiment) Randomization random assignment of experimental units to treatments Range difference between the maximum and minimum values of a dataset Replication repetition of each treatment enough times to help control for chance variation Representative sample sample that possesses the essential characteristics of the population from which it was taken