PRELIM REVIEWER

• Statistics is the study of how to collect, organize, analyze and interpret numerical information from data
• Uses of statistics include: presenting data in concise form, making complex data easy to understand, comparison, enlarging individual experiences, and measuring the magnitude of a phenomenon
• Limitations of statistics:

  • Does not deal with individual measurement
  • Cannot study qualitative phenomena
  • Results are true only on average
  • Data are approximations
  • Can be manipulated
• Quantitative variable: has a value or numerical measurement (e.g., age)
• Qualitative variable describes individuals in terms of a category or group (e.g., male or female)
• Individuals are people, respondents, subjects, or objects included in the study
• Types of variables: Independent, dependent, and extraneous variables

  • Independent variable is the cause and the one to be controlled
  • Dependent variable is the effect and the one being studied
  • Extraneous variable is an unexpected variable that needs to be controlled or eliminated
• Data refers to the number of measurements collected as results of observations
• Population data is the data of the whole, while sample data is the data of a subset of the population
• Two kinds of information sources: primary and secondary data
• Measurement refers to the act of assigning numbers
• Continuous variables can have decimal points, while discrete variables can only be counted in whole numbers
• Scales or levels of measurements include Nominal, Ordinal, Ratio, and Interval
• Nominal is categorical and applies only to qualitative aspects of a variable
• Ordinal is categorical but in numerical form, showing hierarchy, rank, or order without significant data value
• Ratio refers to data with significant value and numerical form starting with 0
• Interval is a scale with no 0-value but meaningful data set, like temperature in Celsius or Fahrenheit
• Statistics is utilized as a tool/language of science in psychology, aiding in the development of psychological research and providing support for psychological phenomena with scientific facts and bases
• Descriptive statistics are used for data summarization and organization to make data comprehensible to the audience
• Some tools under descriptive statistics are proportion, percentage, ratio, rates, stem-and-leaf, and double-stem display
• Proportion is equal to f/N, percentage is equal to f/N (100), and rates are indicators for big data
• Frequency distribution is an organized tabulation of the number of cases falling under a certain class or category
• Class intervals refer to smaller categories or groups containing more than one score value
• Steps in organizing data into grouped frequency distribution table:

  1. Determine how many classes through the 2^k rule where 2^k > n

  2. Determine the class width or intervals through the formula: (h-l)/k

  3. Set up individual class limits (should be mutually exclusive)

  4. Tally the observations into classes

  5. Count the number of items in each class
• Class Frequency refers to the number of observations in each class
• Class Boundaries are used to make limits continuous by adding 0.5 to the upper limit and subtracting 0.5 from the lower limit
• Class Midpoint or Class Mark (Xc) is the mean of the upper and lower limit
• C% = Cf/N (100)
• Graphical presentations include bar graph, histogram, pie chart, and line graph
• Skewness refers to the symmetry of the distribution, categorized as positively skewed, negatively skewed, or no skew
• Measures of position are percentile, decile, and quartile
• Measures of variability include variance, standard deviation, interquartile range, and range
• Kurtosis refers to the peakedness of a curve, categorized as mesokurtic, leptokurtic, or platykurtic
• Research follows a scientific method: state the problem, formulate hypothesis, gather data, analyze data, and make conclusions
• Types of Qualitative Research include Phenomenology, Case Study, Narrative Research, Grounded Theory, Ethnography, and Archival Study
• Quantitative Research Designs include experimental, survey, and correlational research designs
• Two kinds of frequency distribution are: simple frequency distribution and grouped frequency distribution.
• Frequency distribution is also called tally. It is an organised tabulation of the number of cases that fall under a certain class or category.
• Some tools under descriptive statistics are as follows: proportion, percentage, ratio, rates, stem-and-leaf and double-stem display.
• Descriptive statistics is used for data summarization and organisation. This is used so that data may be comprehensible to the audience.