In response to an unknown trigger, the immune system may begin producing antibodies that instead of fighting infections, attack the body's own tissues. Treatment for autoimmune diseases generally focuses on reducing immune system activity.
What's taught in school. Some of the items in standardized achievement tests measure the knowledge or skills that students learn in school. In certain subject areas, such as mathematics, children learn in school most of what they know about a subject.
Test Statistic. The test statistic for an Independent Samples t Test is denoted t. There are actually two forms of the test statistic for this test, depending on whether or not equal variances are assumed. SPSS produces both forms of the test, so both forms of the test are described here.