Descriptive study and descriptive statistics

Educational Research: Descriptive study and descriptive statistics

ELT-718Asst. Prof. Dr. Hasan BEDİR

ÖĞRETMENLER GÜNÜSEVGİLİ MESLEKTAŞLARIM 

ÖĞRETMENLER GÜNÜNÜZÜ EN İÇTEN DİLEKLERLE KUTLAR BAŞARILAR DİLERİM

ONA’DA BİR ZAMANLAR BOŞVER MEMLEKETİ SEN Mİ

KURTARACAKSIN DEMİŞLERDİ

Types of researchResearch Type Purpose Control Time Frame Code Words Example

Nonexperimental (Descriptive)

Describe the characteristics of an existing phenomenon

None or Low

Current “describe” “interview” “review literature

A survey to determine gender differences in language learning

Nonexperimental (Historical)

Relate events that have occurred in the past to current events.

None to Low

Past “past” “describe”

The historical influence of innovations in the approaches and methods improved in language teaching

Nonexperimental (Correlational)

Examine the relationships between variables.

Low to Medium

Current or Past (correlation) future (prediction)

“relationship”“related to”“associated with”“predicts”

What is he relationship between reading and writing achievements of ELT students satisfaction?

Research Type Purpose Control Time Frame Code Words

Example

Experimental To test for a true cause/effect relationship

High Current “Function of”“Cause of”“Comparison between”“Effects of”

The effects of metacognitive strategies in reading comprehension ability of 7th grade primary school students

Quasi-Experimental

To test for causal relationships without having full control

Moderate to high

Current or Past

“Function of”“Cause of”“Comparison between”“Effects of”

The effects of faculties in the achievement of KPSS exam

WHAT METHOD TO USE WHEN?

Differences between groups?

CorrelationalHistorical research

Descriptive research

Are you studying

events that occurred in

the past?

Are you studying

events that primarily occur in

the present?

Are you studying the relationship

between variables (but not the effects

of one on the other)?

Are the participants preassigned to groups?

YesNo

NoYes

Experimental Research

YesNo

Yes

No

Yes

Non-experimental Research

True experimental

Quasi-experimental

Time to reconsider the question

No

Descriptive Research Designs Describes characteristics of existing

phenomena

Provides a broad picture

Serves as basis for other types of research

Studies primarily concerned with determining “what is.”

Dependent & independent variables are not used because there is no attempt to establish causality

Protection against bias

Examine characteristics of a single sample

Descriptive research provides answers to the questions of: Who What Where When How

We cannot answer the question Why? conclusively

Descriptive Researchtakes a “what is” approach

What is the best way to provide access to computer equipment in schools?

Do teachers hold favorable attitudes toward using computers in schools?

What have been the reactions of school administrators to technological innovations in teaching?

Descriptive Research Refers to the nature of the research

question The design of the research The way that data will be analyzed for the

topic that will be researchedThe type of research question will determine

whether descriptive research approach is appropriate to use.

Data Collection Methods

Surveys Interviews

Observations Portfolios

Descriptive Research4. Portfolios

Provide a descriptive measure of student work based on actual performance

Consist of learner-created products that reflect the processes of learning and development over time

Two aspects about surveys:

Survey Content Direct questioning Answering how,

what,and to what extent questions

Usually focus on what was done and what people plan to do in the future

Survey Administration Different data

collection methods Personal interviews Telephone interviews Self-administered

questionnaires (SAQs) Mixed-mode strategy

Surveys Two general formats

Questionnaire Interview

Some people think surveys are easier “Oh, I’ll just type it up and send them out.” Explicit design and thoughtful subject selection

are very important to the concept of control Always pilot test the instrument

Questionnaires & Interviews

Two Extremes Standardized Questionnaires or Structured

Interviews Unstructured (Not Questionnaires) or loose

unstructured interviews

Questionnaires

Two types of questions Base decision regarding structure on three

factors: verbal ability time outcomes

Question Wording and Content Clarity and precision Respondent's ability to provide requested

information Questions of personal or sensitive nature

are more easily released to questionnaires

Format

Appearance and layout of schedule Individuals must be able to follow

directions Follow schematic

questions should not be difficult to follow avoid boredom or being tired and refusing to

complete

Questionnaires May be Distributed by:

Hand

Mail

Email

Online

Questionnaires (cont.) Important points to consider

Response/Nonresponse rates The % of recipients that actually completed the survey (or

didn’t return it) Structure

Overall look of survey Professional? Easy to understand?

Spacing of items or responses Type of items

Open-ended Closed response

Interviews may be conducted

Face-to-face

Over the Telephone

Interviews (cont.) Important points to consider

Structure of interview Very detailed questions and series of questions

Or open-ended? Script for interviewer to read

Characteristics of the interviewer Personal characteristics (ethnicity, age, sex) Communication skills/behavior Appearance

How are responses recorded? Paper Computer Audio or videotape

Observations Observer should NOT be a participant in

the setting Nonparticipant observation

Two types of settings Naturalistic Simulation

Observations (cont.) Important points

Variables to observe should be well-detailed Observable Measurable

Training of observers How was it done? How long did it take? How successful was it (i.e., how consistent are they)?

Interobserver reliability Make sure observers are consistent Recheck at various points throughout study

Observations (cont.) Important Points

How are observations recorded? Paper Computer Videotaped

Recording methods Continuous Interval

Whole Partial Momentary time sampling

Observations (cont.) Important Points

Data types1. Frequency (also called rate or tally)

How often a behavior occurs within a period of time

2. Duration How long a behavior lasts

3. Latency How long before the behavior occurs after a trigger

4. Intensity (also called severity) The amount or force of a behavior

Portfolios Provide a descriptive measure of student

work based on actual performance

Consist of learner-created products that reflect the processes of learning and development over time

Descriptive research: StatisticsTypes of Measurements

standardized achievement scores, classroom observation instruments, attitude scales, questionnaires, and interviews

Statistics Central Tendency (mean, median, mode)Measures of Variability (SD, variance, range)

Statistics...

A set of mathematical procedures for describing, synthesizing, analyzing, and interpreting quantitative data

…the selection of an appropriate statistical technique is determined by the research design, hypothesis, and the data collection technique

descriptive statistics...

…permit the researcher to describe many pieces of data with a few indices

statistics...

…indices calculated by the researcher for a sample drawn from a population

Types of descriptive statistics…

1. graphs

2. measures of central tendency

3. measures of variability

graphs...

…representations of data enabling the researcher to see what the distribution of scores look like

1. Graphs…

frequency polygon pie chart boxplot stem-and-leaf chart

42,  67,  73,  78,  82,  84,  86,  91,  94,  99

measures of central tendency...

…indices enabling the researcher to determine the typical or average score of a group of scores

2. Measures of central tendency…

mode median mean

mode...

…the score attained by more participants than any other score

median...

…the point in a distribution above and below which are 50% of the scores

mean...

…the arithmetic average of the scores

measures of variability...

…indices enabling the researcher to indicate how spread out a group of scores are

3. Measures of variability…

range quartile deviation variance standard deviation

range...

…the difference between the highest and lowest score in a distribution

quartile deviation...

…one half of the difference between the upper quartile (the 75%’ile) and the lower quartile (the 25%’ile) in a distribution

variance...

…a summary statistic indicating the degree of variability among participants for a given variable

standard deviation...

…the square root of variance providing an index of variability in the distribution of scores

Normal distributions of data(the normal curve)...

A bell-shaped distribution of scores having four identifiable properties…

…50% of the scores fall above the mean and 50% of the scores fall below the mean

…the mean, median, and mode are the same value

…most scores are near the mean and, the farther from the mean a score is, the fewer the number of participants who attained that score

…the same number, or percentage, of scores is between the mean and plus one standard deviation as is between the mean and minus one standard deviation

Non-normal distributions of data (skewed distributions)...

A non-bell-shaped distribution of scores where…

…mean < median < mode (a “negatively skewed distribution”)

…mean > median > mode (a “positively skewed distribution”)

measures of relative position...

…indices enabling the researcher to describe a participant’s performance compared to the performance of all other participants

4. Measures of relative position…

percentile ranks standard scores

percentile rank...

…indicates the percentage of scores that fall at or below a given score

standard score...

…a measure of relative position

Types of standard scores...

…z score

…T score

…stanines

z score...

…a statistic expressing how far a score is from the mean in terms of standard deviation units

T score...

…a transformed z score that voids negative numbers and decimals by multiplying the z score by 10 and adding 50

stanines...

…a standard score that divides a distribution into nine parts

…the presence of a correlation does not indicate a cause-effect relationship primarily because of the possibility of multiple confounding factors

Mini-Quiz…

True and false…

…the analysis of the data is as important as any other component of the research process

True

True and false…

…descriptive statistics are normally computed separately for each group in a research study

True

True and false…

…every instrument administered must always be scored accurately and consistently, using the same procedures and criteria

True

True and false…

…tentative scoring procedures must always be tried out beforehand by administering the instrument to the study participants

False

True and false…

…a computer should not be used to perform an analysis that a researcher has never completed by hand or, at least, studied extensively

True

True and false…

…the first step in data analysis is to describe, or summarize, the data using descriptive statistics

True

True and false…

…the number resulting from the computation of a measure of central tendency represents the typical score attained by a group of participants

True

True and false…

…the mean is the most precise, stable index of typical performance that is especially useful in situations in which there are extreme scores

False

True and false…

…standard scores are rarely used in research studies

True

True and false…

…if the extreme scores are at the upper, or higher end of the distribution, it is said to be positively skewed

True

True and false…

…the median of a set of scores corresponds to the 50% percentile

True

True and false…

…a z score expresses how far a score is from the mean in terms of standard deviation units

True

Fill in the blank…

…statistics which permit the researcher to describe many scores with a small number of indices

descriptive statistics

Fill in the blank…

…the values calculated for a sample drawn form a population

statistics

Fill in the blank…

…the score attained by more participants than any other score

mode

Fill in the blank…

…the point in a distribution above and below which are 50% of the scores

median

Fill in the blank…

…the arithmetic average of the scores

mean

Fill in the blank…

…the difference between the highest and lowest score in a distribution

range

Fill in the blank…

… the statistical procedures for describing, synthesizing, analyzing, and interpreting quantitative data

Descriptive statistics

Descriptive Research

The End