Larger Population of Cases. Term

¶ … larger population of cases. Term used to represent the population under study.

Population- set of cases from which a sample is drawn and to which a researcher wants to generalize from.

Frequency- symbolized by f, this is the number of cases with a particular value of a variable, or values of two or more variables.

Measures of Central Tendency- representative values for a set of scores that are considered averages of univariate information.

Mean- arithmetical average of all scores; the sum of cases divided by the number of cases.

Median- value that divides an ordered set of scores in half.

Mode- most frequently occurring score on a variable.

Measures of dispersion- the distribution of statistical frequency; distribution about an average or median

Standard deviation- measure of variation in scores. It is also the square root of the variance.

Range- extent of the frequency distribution; the difference between the minimum and maximum value in a frequency distribution

Variance- square of standard deviation; statistical measure of the spread or variation of a group of values in a sample

Standard error- the standard deviation of a sampling distribution.

Descriptive statistics- refers to methods for summarizing information so that information is more intelligible, more useful or can be communicated more effectively.

Inferential statistics- refers to procedures used to generalize from a sample to the larger population and to assess the confidence we have in such generalizing.

Independent variable- variable determining the value of others; the variable in a mathematical statement whose value, when specified, determines the value of another variable or other variables

Dependent variable- an element in a mathematical expression that changes its value according to the value of other elements present

Confounding variable- variable that may be confused for the independent variable; commonly makes researchers fail to distinguish between the independent variable and confounding variable

Sampling- the process of selecting a sample group to be used as the representative or the random sample

Normal distribution- a probability frequency distribution for a random variable that takes on a bell shape figure, symmetrical about the mean.

Part 2

One of the important issues that this type of statistical sampling conducted by the substitute teacher was her choice of students to inquire about their test results. In a class size of 30, 5 students hardly represent the whole class; in fact, in order to accurately determine the performance of the class as a whole, it is recommended that all students be asked of their test results. The sub-teacher can also generate a sample, group of students who will represent the total population, which is the whole class. The sample should be objectively chosen, and since the method of choosing the students to report on their exam performance was based only on the fact that they all belonged to the front row of the class, then the sample generated by the teacher is biased. An alternative to this problematic method of sampling would be to choose one student every row, grouping all the scores of each row representative, and getting the average of these scores. The average of the students' performances would then become the teacher's basis in assessing the class's performance.