How to gather DATA

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How to gather DATA
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Process of statistics

• 1) Identify the research objective
• - Create a detailed question to a specific group
  that is to be answered.
• 2) Collect the information needed to answer the
  question.
• 3) Organize and summarize the data.
• 4) Draw conclusions from the information and
  generalize it to the population.

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Surveys

• Statistical surveys collect quantitative
  information from a specific population. 
• A survey may focus on opinions or factual
  information.
• Surveys may involve answering a questionnaire or
  being interviewed by a researcher. 

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SURVEY
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How will data be collected?

• Include the entire population
• Simple Random Sample number generated (equal
  chance of selection)
• Stratified Sampling broken into groups and then
  random sampled
• Systematic Sampling is obtained by selecting
  the k th individual from population
• Cluster Sampling is obtained by selecting all
  individuals within a collection or group

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Experimental study

• The researcher takes measurements, or surveys,
  the sample population. 
• The researcher then manipulates the sample
  population in some manner. 
• After the manipulation, the researcher
  re-measures, or re-surveys, using the same
  procedures to determine if the manipulation
  possibly changed the measurements.
• During a "controlled" experiment, the researcher
  will separate the sample population into groups
  with one group established as the control group. 

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Experimental Study Example

• A group of students is interested in knowing if
  the number of times they can sink a basketball is
  related to the color of the basketball. The
  students shoot a series of baskets and record
  their success using a regulation colored
  basketball.  They then switch to a blue colored
  basketball and shoot the same series of baskets. 
  A statistical analysis is performed.

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Observational Study

• The sample population being studied is measured,
  or surveyed, as it is. 
• The researcher does not influence the population
  in any way or attempt to intervene in the
  study.  
• There is no experimental manipulation.  Instead,
  data is simply gathered and correlations are
  investigated.

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Observational Study Example

• A group of students is interested in knowing if
  there is a correlation between attending an SAT
  Prep class and scores achieved on the SAT
  Examination.  The students use a survey to
  collect their data from both students who took an
  SAT Prep class and those that did not take an SAT
  Prep class.  A statistical analysis is performed.
  

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Biased Sample

• Who collected the data?   Does the group
  collecting the data have an interest in how the
  results turn out?
• Example  A study on the hazards of cigarette
  smoking being done by a tobacco company. (may not
  be reliable findings - conflict of interest)
• Is the study a recent study, or did it occur
  decades ago?  Could recent developments have
  changed the findings? 
• Example  Decades past, second-hand cigarette
  smoke was found to not be hazardous.  More recent
  findings prove that this is not true.(findings
  should be current)

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Biased Sample Cont

• What is the sample size of the study?  How many
  people/items were studied?
• Example  A study is done on the favorite color
  of 14 year olds.  The sample group for the study
  is Mrs. Smith's third period class containing 20
  students.(too few participants to generalize a
  finding to all 14 year olds)
• Is the data from a primary source?  Or has the
  data been "condensed" by another group? 
• Example  The US Census Bureau collects data on
  US populations.  A tabloid magazine publishes a
  synopsis of the findings.(the most reliable
  information comes from the original source -
  avoid the "Reader's Digest" condensed version by
  another publisher who may be interpreting the
  findings)

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Applying what we have learned

• What is the average distance of a HS students
  house to Newfane High School?
• How will we collect this information?
• Survey each student?
• MapQuest everybody?
• Internet polling?
• Not reliable!
• Take a sample of the population? A random sample
• How will we organize this data?
• Charts, graphs, tables?
• Is there any Bias or Flaws with this study?

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