922 - Statistics exercise(Courtesy of Dr. Shira Farby)
The exercise below has two parts.
Part I (sections B & C) should be submitted by 2/12/12
Part II (sections D-G) should be submitted by 6/1/13
All submissions by email.Late submissions will NOT be accepted
- Experiment description
A linguistic experiment tested 58 children who are Russian-Hebrew bilinguals (speak Russian at home, and Hebrew at the preschool). In abackground information form the age of the children in months was marked, as well as how long they have been exposed to Hebrew. Two questions in the background information form were to what extent the child's mother uses Russian (more / less) and to what extent the child's mother uses Hebrew (more/less). As theses are separate questions, both can be answered as "more".
One part of the experiment was on social identity, and the children were asked to rate (on a scale of 1 to 10) to what degree they agree with the following social labels: Russian, Israeli, Ivri, Jewish.
The second part of the experiment was linguistic, and the children were asked to repeat sentences in Hebrew and Russian. The score of two linguistic indicators from the repeated sentences was computed separately (repeating prepositions correctly, repeating plural inflection correctly).
Part I – for 2/12/12
- Design
- Name 3 independent variables. What is the type of their scale?
- Name 3 dependent variables. What is the type of their scale?
- How many conditions are in the social part? Give them names.
- How many conditions are in the linguistic part? Give them names.
- Hypothesis
- Choose one part of the experiment (social/linguistic), and phrase for it an experimental hypothesis, using the excel table as your guideline. Remember that the hypothesis predicts an effect of independent variable(s) on dependent variable(s).
- What is the null hypothesis for your hypothesis?
- What is the direction of your hypothesis?
Part II – for 6/1/13
- General computations
- For the variable "age" compute the mean and median.
- For the variable "Length of exposure to Hebrew" compute the mean and standard deviation.
- For the variable "Mother in terms of Russian use" compute the percent of "more" responses.
- For the variable "Mother in terms of Hebrew use" compute the ratio of "more" responses.
- For the variable "How much do you agree: Ivri" compute minimum, maximum and range.
- For the variable "How much do you agree: Israeli" construct a frequency table.
- For the variable "preposition repetition, Hebrew" compute the proportion of correct repetition (for each child), and add this as a new column to the excel table.
Thinking question: what is the difference between the new column (proportion of prep repetition) and the old grade (prep repetition)?
- For the variable "preposition repetition, Russian" construct a column with percent of correct responses for each child, and fill in the following table:
% of correct preposition (Russian) / Frequency / cumulative frequency / percentile
40-70
71-80
81-90
91-95
96-100
Total N / 58
Optional: generate a frequency graph for this variable.
- Descriptive statistics
- Based on your hypothesis, describe the findings in terms of conditions and effects:
In a _____ design of _____ conditions, the effect of ______as the independent variable(s) on ______as the dependent variable(s) was measured in a ______task. (N=__)
- Construct the appropriate table to report mean and standard deviation of all conditions.
Tips:
Choose conditions that you are sure about what they represent.
Make sure the scores of the condition match before you compute means and standard deviations. You may have to add new columns to re-calibrate variables (for instance, month/years).
- Optional: generate a histogram of the findings.
- Initial Conclusions
- Do the findings of this group suggest that your hypothesis is in the right direction?
- Do the findings support the effect of the independent variable(s)?
- Inferential statistics
- Name the statistical test you will use to see if the effect is significant.
- How many degrees of freedom do you have?
- How will you compute the critical value for rejecting the null hypothesis? ( or /2).