Monday, August 14, 2017
Sunday, April 16, 2017
Friday, April 14, 2017
Friday, January 13, 2017
Fulbright Alumni Grant Activity 2016
Suresh's Alumni Grant Activity 2016:
A Lecture Presentation
When: December 18 – 19’ 20016.
Where: At Dr. D.D. Pant Memorial Children's Science Exploratory and Government Girls Inter College, Berinag (Uttarakhand), India.
For Whom: Students,
teachers (from four different schools) and community members from a highly underserved
population in and around a small town Berinag, Uttrakhand, India.
Summary of the proposed project: - I have utilized my alumni grant 2016 to educate students, teachers and
community members from a highly underserved population in and around a small
town Berinag, Uttrakhand, India through a workshop and a lecture presentation
during December 18-19’ 2016. Workshop and lecture presentation were based on my alumni grant activities in the past and my Fulbright Distinguished
Awards in Teaching Program experience in the United States. Proposed workshop was a first-hand experience to the students and teachers by involving them
into hand-on activities using low cost pedagogical tools based on games and
models. Moreover, it helped them to expose to the experiential learning
opportunities.
The workshop helped me to promote involvement of girls in educational activities in such rural areas as it comprized 60% girls and 40% boys, along with the teachers, from different schools in Berinag.

The lecture
presentation was a dissemination of my Fulbright capstone project, described outcomes
of the current workshop and helped propagating outcomes of all alumni grant
activities that I have organized till now.
The objectives of the activity: -
The four-fold purpose of my alumni grant is
(ii) To educate students, teachers and community from a highly underserved population through experiential
learning opportunities by exposing
them to ‘learning by doing’ activities
using games and model first hand,
Descriptions of the proposed activity:
A description of the
need for the project and any activities I have already implemented to address
this need: - The students in the demographics such as Berinag, Uttrakhand,
India, particularly those from Government schools (target population of my
alumni grant), does not have resources such as funds, tools and other supporting
learning material.
There is a strong need to educate students, teachers and the community
in such areas about alternative resources of developing low cost teaching-learning
tools by using surrounding material. This project will encourage them to use
low cost models and games, available in their surroundings, for teaching
-learning purposes and thereby will make them self-resourced.
Workshop and
lecture of the project would also help them to make their knowledge concrete
and experience based.
My alumni grant activities organized in the past (2013, 2015) were
focused on training the trainers (teachers) from Delhi and NCR (National
capital Regions), which were highly successful. Teachers benefitted from those
activities use models and lesson plans, that they were able to develop during
these alumni grant activities, in their schools.
Acknowledgements: The U.S. Department of State & EPSO, Texas A&M University.
Thursday, January 21, 2016
Wednesday, November 11, 2015
Regression and Regression Constants....
Regression: It is a prediction. Deriving an equation
for predicting one variable from the other.
Algebraically, Errors of prediction = (Y
- ^Y)
Least squares linear regression: In a cause
and effect relationship, the independent
variable (X) is the
cause, and the dependent variable (Y) is the effect. Least squares linear
regression is a method for predicting the value of a
dependent variable Y,
based on the value of an independent variable X.
The Least Squares Regression Line: It
is a series of points arranged in a straight line that tells how much better the prediction is. Linear
regression finds the straight line, called the least squares regression line that best represents observations in a bivariate data set. Suppose Y is a dependent variable, and X is an independent variable, the
population regression line cab be written as:
Y = b X + a
In this linear equation, ‘b’ is the beta coefficient
and ‘a’ is the Y- intercept of the regression line.
Line of Best
Fit (Least Square Method):
Minimizes the squared difference (squared deviations) between Y and ^Y (because
we can have more than one predicted value for one X value). This method is a more accurate way of
finding the line of best fit. A line
of best fit is a
straight line that is the best
approximation of the given set of data. It is used to study the nature of
the relation between two variables.
A line of best fit can be roughly
determined using an eyeball method by drawing a straight line on a scatterplot
so that the number of points above the line and below the line is about equal
(and the line passes through as many points as possible).
Steps to
find the equation of line of best fit:
1. Calculate the mean of
the x-values and the
mean of the y-values.
2. Find the slope of the
line of best fit
3. Compute the Y-intercept of the line by using the formula.
4. Write equation of the
line (Y = bX + a)
Properties of Regression
Line: When the regression parameters (a & b) are defined by the equation above,
the regression line has the following properties:
- The
difference between obtained and predicted value (Y - ^Y) is called an
error of prediction called residual.
We want to find a line that minimizes the squared difference between Y and
^Y and is known as least square regression line and the approach is called
least squares
regression.
- Two
important measures of the size of an effect in regression are r2 and r.
- The
regression line passes through the mean of the X values (x) and through the mean
of the Y values (y)
or we can say that it passes through the centroid of the data.
- The
regression constant (a) = Y-intercept of
the regression line.
- To
use the regression equation technique described in the text, we must have a
logical pairing of the scores
on the two variables and a linear
relationship between them.
Intersection
of two means fall on the regression line.
Regression
coefficient (b, Slope, nonstandardized): The amount of change in Y for a one – unit change in X. Or
the rate at which Y change with change in X. Larger
the value (size) of the regression coefficient, the steeper the slope. It is (b) which a measure of how strongly each predictor
variable influences the criterion (outcome) variable.
byx = rxy (SDy / SDx);
when Y – Outcome, X – predictor
And,
bxy = rxy
(SDx / SDy); When X – Outcome, Y – predictor
‘b’ is measured in units
of standard deviation. For example, a beta value of 2.5 indicates that
a change of one standard deviation in the predictor variable will result
in a change of 2.5 standard deviations in the outcome (criterion) variable.
1. ‘b’
= 1.08 means when X increases by 1 point, outcome increases by 1.08.
2. On multiplying two slopes b y·x and
b x·y we are left with the square of the correlation coefficient which tells about percentage of variance of both
variables together. It tells the percentage accuracy in predicting Y. It is better to have the knowledge of
correlation coefficient to predict the outcomes.
3. If b coefficient
is positive, the relationship of predictor variable with dependent variable is
positive (e.g., the greater the IQ the better the grade point average) and if b coefficient is negative then the
relationship is negative (e.g., the lower the class size the better the average
test scores).
4. If b coefficient is equal to 0 then there
is no relationship between the variables.
5. ‘b’
can be anything (when b = +, r = +, and b = -, r = - but b = +, r = - & vice versa is not
possible)
6. Many
lines may have same slope (b) but cannot have the same intercept ‘a’ altogether
(‘a’ is the unique identification of a line).
Beta coefficient (b, standardized regression coefficients): It is the change in Y for one unit standard deviation change
in X. It
is the slope of the regression line
when both X and Y variables are converted
to standardized z-scores. Thus, higher the beta value the greater the
impact of the predictor variable on the criterion variable.
1.
When we have only one predictor variable in our model,
then,
Beta (b) = rxy.
2.
When we
have more than
one predictor variable, we cannot compare contribution of each
predictor variable by simply comparing
the correlation coefficients.
The beta coefficient allows to make
such comparisons and to assess the
strength of the relationship between each predictor variable to the criterion
variable
Interpreting regression constants:
The regression coefficient
(b) is the average change (increase
or decrease depending on +ve or –ve b) in
the outcome variable (Y)
for a 1 – unit change in the predictive variable (X).
Slope (b coefficient) is a measure of how strongly each predictor variable
influences the criterion (outcome) variable. Higher the beta value the greater the
impact of the predictor variable on the outcome variable. Relationship is positive if b coefficient is positive and vice
versa.
Regression constant ‘a’; Y – intercept: That anchors our line.
The
constant term ‘a (regression constant)’ is the value at which fitted line (Line
of best fit) crosses the y-axis. It is used as a ‘correction factor’ when using particular
values of the x's to predict y. If
we don’t include the constant, the regression line is forced to go through the
origin which means all of the predictors and the outcome variables must be zero at
that point.
Scatterplot (what is it and why is it required?)..
Scatterplot: It is a graphical (pictorial)
interpretation of the linear correlation between two continuous (interval /
ratio) variables, predictive and outcome, plotted in X and Y axis respectively.
Why Scatterplot?
1.
Because describing a
relationship through a number is not enough, we need to look at the
relationship in a scatterplot or how points very (bunched-up) around regression
line in a scatterplot.
2.
Graph (scatterplot)
also helps in detecting the homoscedasticity (variability of points around the
regression line) in a relationship which is rectified through transformation.
3.
Graph (scatterplot)
tells about the outliers in the data,
which are the threats to the interpretation
and needs to be omitted.
4.
Scatterplot determines the situations where
the correlation is curvilinear. Simply reporting r = 0 might be misleading because a relation
still exists which might not be a linear one.
Two Characteristics
of a scatter-plot:
1.
The slope of the scatter-plot, and
2.
The degree to which the points in
the scatter-plot cluster around an imaginary line representing the slope.
These notes are written by S C Joshi during EPSY 635 Course, Fall 2015, Texas A&M University. Acknowledgements to Dr. Bob Hall, Professor, EPSY, Texas A&M University for his assistance in understanding these terms during the course
Covariance: It
is a measure of the degree to which two random variables (X, Y) change
together.
Covxy
= Sum of products of errors / (n-1)
r2 (Coefficient of determination):
Indicates
how well data points fit a line or curve. It is mainly used in models to
predict future outcomes or test hypotheses on the basis of other related
information.
The squared
correlation coefficient (r2) is
the proportion of variance in Y that can be accounted for by knowing X.
Conversely, it is the proportion of variance in X that can be accounted for by
knowing Y. Further, I can say that it is a statistic
which indicates the percentage change in the amount of the outcome variable
(dependent) that is ‘explained by’
the changes in the predictor variable (independent). In other words, shared
/ common variance, means how much percentage of the relationship can be
explained by the regression (or predicted) and rest is unexplained. It is the
indicator of accuracy of a prediction. We can also call it a proportion of the variance in outcome variable (Y)
that is predictable from the predictor variable (X) or it is the
fraction of the variation in Y that is explained by least-squares
regression of Y on X.
1.
The coefficient of determination
ranges from 0 to 1 (proportion or percentage, cannot be more than 1 or 100%
respectively).
2.
It is important to note that a high coefficient of
determination does not guarantee that a cause-and-effect relationship exists.
However, a cause-and-effect relationship between the independent variable and
the dependent variable will result in a high coefficient of determination.
3.
An R2 of 0 means
that the dependent variable cannot be predicted from the independent variable.
4. An R2 of 1 means the dependent
variable can be predicted without error from the independent variable.
These notes are written by S C Joshi during EPSY 635 Course, Fall 2015, Texas A&M University. Acknowledgements to Dr. Bob Hall, Professor, EPSY, Texas A&M University for his assistance in understanding these terms during the course
Threats to Correlation Coefficient...
Threats to PPMCC (Factors affecting
correlation):
1.
Outliers:
the data that stands out in the scatterplot does not contribute to the
relationship and must be omitted. (for small group outlier has large effects).
Outliers does not go with the linear relationship (must have performed poor in
exam 3 and outstanding in exam 4). Value of r will increase if the outliers
are removed and more accurate
depiction of the relationship between the predictor and the outcome measures because outliers
are the threats to the PPMCC and results decrease in r value. So, on removing
outliers data shows better liner relationship thus increase in r value.
2.
Combined groups: Two
groups separately may not show any relationship individually but together may
show a strong relationship.
3.
Extreme groups: There
is no relationship (r = 0) between
two variables for low performing groups
and high performing groups individually, but together they show the
relationship.
4.
Range restriction (truncated range): If we restrict the range (means accept only high SAT
scorers we will not be able to see the relationship on how low SAT scores are
going to do in college so) relationship is going to be lower. Truncated range
lowers the correlation.
5.
Nonlinear relationship (curvilinear
relationship): is not explained by PPMCC.
Assumptions Underlying the Pearson Product Moment Correlation Coefficient....
Assumptions Underlying
the PPMCC: PPMCC is appropriate
when three conditions exists: underlying
measurement scales for the variables being correlated must be interval or ratio level, Scores for each variable should be normally distributed (no
skewness should be there), relationship between the two
variables should be fundamentally linear.
1.
The underlying measurement scales for the variables
being correlated must be interval or ratio
level (i.e., they are continuous).
Examples
of variables that meet this criterion include revision time (measured in
hours), intelligence (measured using IQ score), exam performance (measured from
0 to 100), weight (measured in kg), and so forth.
2.
Bivariate
Normality (Bivariate normal distribution): Scores for each variable
should be normally
distributed. No skewness, neither positive nor negative should be
there.
3.
Relationship between the two variables should
be fundamentally linear.
4.
There should be no
significant outliers (single data points within the data that do not
follow the usual pattern).
5.
Homoscedasticity: It means variance around
regression line should be same for all values of predictor variable (X). A
relation is called heteroscedastic when all the points very (bunched up) near
the regression line. Homoscedasticity is
violated when there is much more variability (points are scattered away
from the regression line) around the regression line.
Serious violations in
homoscedasticity (assuming a distribution of data is homoscedastic when in
actuality it is heteroscedastic) result in underemphasizing
the Pearson coefficient. Assuming homoscedasticity assumes that
variance is fixed throughout a distribution.
Heteroscedasticity is
caused by non-normality of one of the variables, an indirect relationship
between variables, or to the effect of a data transformation.
Heteroscedasticity is not fatal to an analysis, the analysis is weakened, not
invalidated. Homoscedasticity is detected with scatterplots and is
rectified through transformation.
These notes are written by S C Joshi during EPSY 635 Course, Fall 2015, Texas A&M University. Acknowledgements to Dr. Bob Hall, Professor, EPSY, Texas A&M University for his assistance in understanding these terms during the course
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