Statistics is a science that deals with the collection, organization, presentation, analysis and interpretation of data.
Descriptive Statistics consists of methods concerned with collection, organization, summarization and presentation of a set of data.
Inferential Statistics comprises of those methods concerned with making predictions or inferences about an entire population based oninformation provided by the sample
Population consists of the totality of all the elements or entities from which you want to obtain information
Sample is a subset of a population.
Census is the process of collecting information from the population
Survey is the process of collecting information from the sample
Parameter is a summary or numerical measure used to describe a population
Statistic is a summary or numerical measure used to describe a sample
A constant is a characteristic or property of a population or sample which makes the members similar to each other.
Variables are any characteristic or information measurable or observable on every element of the population or sample
Qualitative variables are variables that indicate what kind ofa given characteristic an individual, object, or event possesses
Quantitative variables are variables that indicate how much agiven characteristic an individual, object, or event possesses
The types of Quantitative Variables are (1) Discrete and (2) Continuous.
Discrete Variables are variables whose values are obtained through the process of counting.
Continuous Variables are variables whose values areobtained through the process of measuring.
The types of Qualitative Variables are (1) Dependent and (2) Independent.
A Dependent variable is a variable which is affected by anothervariable.
Independent Variables are variables which affect dependentvariables.
The scales of measurement of variables are (1) nominal, (2) ordinal, (3) interval, and (4) ratio.
Nominal scale are variables whose values are simply labels or names orcategories without any explicit or implicit ordering of the labels.
Nominal scale is the lowest level of measurement also known as the categorical scale
Ordinal scale are variables whose values are simply labels or names or categories with an implied ordering in these labels.
Distance between 2 variables in an ordinal scale cannot be determined.
Interval scale are variables whose values can be ordered and distancebetween any two labels are of known size.
Interval scale is always numeric with no true zero point.
Ratio scale are variables that have all the properties of interval scales plus they have a true zero point.
There are 3 types of presentation of data: textual, tabular, and graphical.
A textual presentation is when Data are presented in paragraph form. It involves enumeration of important characteristics, giving emphasis on significant figures and identifying the important features of the data.
Tabular presentation is the presentation of data through tables.
A frequency distribution table is a tabular summary of data showing the frequency of items in each of several non-overlapping classes.
The steps in constructing a frequency table:
Determine the range, denoted by R.
Decided on a number of classes, denoted by k.
Compute the class size, denoted by c.
Identify the class intervals, CI.
Identify the frequency of each CI or tallying.
Class size is the Range (R) divided by number of classes (k).
Class Boundaries are the numbers that separate classes without forming gaps between them.
Class Mark or Midpoint is the middle value of each data class. To find the class midpoint, average the upper and lower class limits of each CI.
The relative frequency is obtained by dividing the frequency of the given class by the total number of observations.
Cumulative frequency of a data class is the number of data elements in that class and all previous classes.
Less than CF is the total number of observations within a class whose values do not exceed the upper limit of the class.
Greater than CF is the total number of observations within a class whose values are not less than the lower limit of the class.
Bar charts are for discrete data, while histograms and line graphs are for continuous data.