# tTestPairedSoTL.R
# paired t test for SoTL

# Import Data From Spreadsheet (Step 1)
# -------------------------------------
# Data: 2 columns of numeric data, blank cells are ok, but no cells with words.
df = read.table(file = "clipboard", sep = "\t", header = TRUE);
df;               # display student data in console.

# Clean data in R (remove the rows with NA's)(Step 2)
# ----------------------------------------------------
dfc = na.omit(df) # dfc = df with rows with blank cells removed
dfc

# Find the mean and standard deviation of the quiz scores (Step 3)
# ----------------------------------------------------------------
mean(dfc$before);   # the mean of the before scores
sd(dfc$before);     # the standard deviation of the before scores 

mean(dfc$after);   # the mean of the after scores
sd(dfc$after);     # the standard deviation of the after scores 

# Create histogram of data (Step 4)
# --------------------------------
hist(dfc$after - dfc$before, 
 main = "Histogram of quiz score differences\nPost-treatment minus pre-treatment",
 xlab = "Percent",
 col = "green" );

# Do the paired t-test (Step 5)
# -----------------------------
t.test(dfc$after - dfc$before, alternative = "greater", mu = 0);

# End of Script
#---------------------------------------------