Standard Scores (z) and Normal Distributions, escribing Relationships: Correlation, Regression

1

Prediction of I .Q . based on number of days breastfed

There would be two variables in the study

The predictor variable is number of days breastfed as a baby

The criterion variable is I .Q 0 .05 . We use this because it 's the standard for non-medical testing

Yes , whether or not there have already been the same or even similar studies made

The conclusion would tell whether or not number of days breastfed as a baby can predict the individual 's I .Q . when tested later on in life p

Research Proposal

The goal is to determine whether Intellectual Quotient (I .Q ) can be significantly predicted by the number of days which an individual has been breastfed as a baby . A random sample of 30 individuals would be selected and their mothers would be interviewed for the number of days which the individuals were breastfed . Afterwards , the subjects ' I .Q would be tested . Data collected would be analyzed using regression analysis . The linear equation predicting I .Q . from number of days breastfed would be tested for significance at a 0 .05 confidence level

2

Correlation between number of absences and high school GPA

I would have two variables

The sample size should be greater than 30 so as to be able to generalize better

Correlation is usually tested at 0 .05 confidence level so that 's what will be used

Again , one should always ask whether or not the study has already been done

Whether or not there is a significant relationship between number of absences and high school GPA

Research Proposal

The goal is to determine whether there is a significant relationship between number of absences and GPA . A sample of 30 newly graduates will be selected . Data from high school records on each subjects ' number of absences in their entire stay in the school and their GPAs . The data will be tested for correlation at a 0 .05 confidence level

3 (Z z (125 - 100 /15 0 .2

P (Z z (82 - 100 /15 0

P (Z z (109-100 /15 ) -

(Z z (91-100 /15 0 .4

2[1 -

(Z z (3 .5-3 .2 /0 .3 0 .4

Proportion : Approximately 1 out of 6 .5

P (Z z (2 .5-3 .2 /0 .3 0 .9

Proportion : Approximately 1 out of 101 .8814589

P (Z z (3 .75-3 .2 /0 .3 0 .8

Proportion : Approximately 1 out of 29

Z[P (z 0 .9] 1 .6

x 1 .6 (0 .3 3 .2 3

6

I will tell the person that it does not because standard scores are simply a reflection of how the individual did with respect to the population . It 's an entirely different measure from the raw scores which tests how well the individual did with respect to the questionnaire

7

The scatter plot seems to show a negative relationship between x and y and so a curvilinear trend does not exist

8

No it will not . Because r is a correlation between two quantities...