MMW

Midterm

Data

are the facts/ information, figures or observations collected from real life situations

• collected information

Data Management

the process of collecting, organizing, storing, processing, presenting and interpreting data in order to make informed decisions

• turn raw data into USEFUL INFORMATION

Statistics

• Backbone of data management (main tool used in data management)

• science of collecting, organizing, presenting, analyzing and interpretation of data

Process of Data Management

• Data collection

• Data organization

• Data processing/ analyzing

• Data presentation

• Data interpretation

Descriptive Statistics

organizes and summarizes data statistical tool: Mean, Median, Mode, and graphs (bar, pie and pictograph). “what does the data show?”

Inferential statistics

Make predictions or a conclusion, Hypothesis testing, regression and correlation. “What can we conclude?”

Population

entire group

Sample

subset of population

Variable

measurable characteristics

Types of Variable

• Qualitative (categorial)

• Quantitative (Numerical)

  • Discrete (countable)

  • Continuous (measurable)

Data collection

• Survey/ Questionnaire

• Interview

• Experiment

• Focus group discussion

• Existing records

• Observation

Gathering raw materials

Level of measurement

• nominal

• ordinal

• interval

• ratio

Numerical

• ratio

• interval

Categorical

• ordinal

• nominal

Nominal

• data are classified into categories without any order or ranking

Ordinal

data are categorized with a meaningful order, but the intervals between values are not equal . Can be placed in rank order

Interval

data have order and equal intervals but there is no true zero

Ratio

Data have order, equal intervals and a true zero

Data Organization

• Array

• frequency Distribution table

  • Ungrouped freq. dist’n

  • Grouped freq. dist’n

Arranging data into table or categories

Array

Listing the numerical data in ascending order or descending order

Frequency Distribution table

it categorizes the numerical data into classes or interval

Data Presentation

• Textual form

• Graphical form

• tabular Form

using tables and graphs

Textual form

data are described using words and sentences

Graphical form

data are presented visually using graphs or charts. It must be accurate, simple, clear and attractive.

Tabular form

data are arranged in rows and columns

Pie chart

parts of a whole

Bar graphs

compare categories

Scatter plot

relationship between two variables

line graph

trends over time

histogram

distribution of data

frequency table

summarizes data

stem and leaf plot

show data spread

Box and whisker plot

data distribution, Outliers

Group frequency Distribution

when the range of the data is large, the data must be grouped into classes that are more than one unit in width

Cumulative frequency (CF)

indicates the number of observations that fall below or above a specified upper boundary. It can be obtained by adding the frequencies of a distribution

Measures of central tendency

• measure of average

• Mean, median, mode

Mean

• x- bar

• arithmetic average

• found by adding the values of data and dividing by the total number of values

Median

• x - curl

• midpoint of the data array. Arrange the data in order and select the middle point

• odd and even rule

Mode

• x- hat

• value that occur most often in the data set. A data can have more than one mode or no mode at all

  • 1 - unimodal

  • 2 - bimodal

  • 3 - trimodal

  • 4 - abuse multimodel

  • 0- no mode

Weighted Mean

type of mean that considers an additional factor. It is used when the values are not all equally represented

Positive skew

tail on the right

Negative skew

Tail on the left

Symmetrical

balance distribution or evenly distributed on the side of the mean

Range

• show spread of data

• highest value minus the lowest value

• symbol R

Variance

measures average squared deviation

Standard deviation

measures spread in actual units (or the square of the variance)

Empirical rule (NORMAL DISTRIBUTION)

describe distribution of data in a bell shaped curve

• 68% within 1 SD

• 95% within 2 SD

• 99,7% within 3 SD

Z - scores

measures distance from mean in standard deviations

Quartiles

divided data into 4 parts

Deciles

divided data into 10 parts

Percentiles

Divide data into 100 parts